- Computer power supply
- Power
- Active or passive PFC?
- Cooling the power supply
- Connectors and cables
- Brands and manufacturers
- From the history
- Development prospects
Computer power supply
Choosing the right power supply for your computer can sometimes not be as easy as it sounds. Stability depends on this choice, as well as the service life of all used PC components, and you need to approach the issue of choosing a power supply seriously. In this review, we will try to consider the main points that will help you make the right choice.
Power
The following constant voltages are present at the output of the power supply: +5 V, +12 V (also +3.3 V), and - auxiliary (minus 12 V and + 5 V in idle). The main load is now "accepted" to load the +12 V line.
The output power (W - Watt) is calculated using a simple formula: it is equal to the product of U by J, where U is the voltage (in Volts), J is the current (in Amperes). Voltages are constant, therefore, the more power, the more current should be along the lines.
But it turns out that everything is not simple here either. With a strong load on the combined +3.3 / +5 line, the power on the +12 line may decrease. An example is the marking of the power supply unit of the budget Cooler Master brand (models RS-500-PSAP-J3):
The maximum total power on lines +3.3 and +5 is 130W (which is indicated on the package), but the maximum power on the "most important" line + 12V is equal to 360W.
But that's not all. Pay attention to the inscription below:
3.3V and + 5V and + 12V the total power should not exceed 427.9 W. As if, theoretically (looking at the “table”), we “see” 490W (360 plus 130), but here - only 427.9.
What this will give us in practice: if the load on the + 3.3V and 5V lines is a total of, say, 60W, then subtracting 427.9 from the power supplied by the manufacturer, i.e. 427.9 - 60, we get 367.9W. We only get 360 watts on the + 12V line. From which comes just the "main consumption": current to the processor, video card.
Automatic power calculation
To calculate the power of the power supplies, you can use the calculator in your browser: http://www.extreme.outervision.com/psucalculatorlite.jsp. Although it is in English, you can figure it out. There are a lot of such services on the Internet.
In general, here you can choose almost everything you need, including a specific type of CPU, motherboard format (micro-ATX or ATX), the number of memory sticks, hard drives, fans ... To calculate, press the rectangular Calculate button. The service will issue: both the recommended and the minimum possible power value (in watts) for your system.
However, from experience, we can assume: an office computer (with a dual-core CPU) can be content with a 300W power supply. For home (gaming, with a discrete video card) - a 450 - 500W power supply is suitable, but for powerful gaming PCs with a "top" (top) card (or two, in Crossfire or SLI mode) - Total Power (total power) starts from 600 - 700W.
The central processor, even at the maximum possible load, consumes 100 - 180W (with the exception of 6-core AMD), a discrete video card - from 90 to 340W, the motherboard itself - 25-30W (memory stick - 5-7W), hard drive 15- 20W. Keep in mind that the main load (processor and video card) falls on the "12V" line. Well, it is advisable to add a power reserve (10-20%).
Efficiency - coefficient of efficiency
An important criterion will be the efficiency of the power supply. Coefficient of performance (COP) - the ratio of the useful power supplied by the power supply to the power consumed by it from the network. If the PC power supply circuit contained only a transformer, its efficiency would be about 100%.
Consider an example when a power supply unit (with a known efficiency of 80%) provides 400W of output power. If this number (400) is divided by 80%, we get 500W. A power supply with the same characteristics, but with a lower efficiency (70%), will consume 570W.
But - do not take these numbers "seriously". Most of the time, the power supply is not fully loaded, for example, this value can be 200W (the computer will consume less from the network).
There is an organization whose functions include testing power supplies for compliance with the level of the declared efficiency standard. At the same time, 80 Plus certification is carried out only for 115 Volt networks (common in the USA), starting from the 80 Plus Bronze "class", all units are tested for use in a 220V mains. For example, if certified in Class 80 Plus Bronze, the PSU is 85% efficient at half capacity and 81% at rated capacity.
The presence of a logo on the power supply indicates that the product meets the certification level.
Pros of high efficiency: less energy is removed "in the form of heat", and the cooling system, accordingly, will be less noisy. Secondly, the savings in electricity are obvious (although not very large). The quality of "certified" power supply units is usually high.
Active or passive PFC?
Power Factor Correction (PFC) - power factor correction. Power Factor - the ratio of active power to total (active plus reactive).
By the load, reactive power is not consumed - it is 100% given back to the network, in the next half-period. However, with an increase in reactive power, the maximum (for the period) value of the current strength increases.
Too much current in the 220V wires - is it good? Probably not. Therefore, they struggle with reactive power whenever possible (this is especially true for really powerful devices that "cross" the 300-400 Watt limit).
PFC - can be passive or active.
The advantages of the active method:
The Power Factor is close to the ideal value (power factor), up to a value close to 1. At PF = 1, the current in the 220V wire will not exceed the value of "power divided by 220" (in the case of lower PF values, the current is always slightly more).
Disadvantages of active PFC:
The complexity increases - the overall reliability of the power supply decreases. The active PFC system itself requires cooling. In addition, it is not recommended to use active correction systems with auto-voltage in conjunction with UPS sources.
Advantages of Passive PFC:
There are no drawbacks to the active method.
Flaws:
The system is ineffective at high power values.
What exactly should you choose? In any case, when purchasing a power supply unit of lower power (up to 400-450W), you will most often find the PFC of a passive system in it, and more powerful units, from 600 W, are more often found with active correction.
Cooling the power supply
The presence of a fan for cooling in any power supply unit is considered to be the norm. The fan diameter - can be equal to 120 mm, there is a variant of 135 mm and, finally, 140 mm.
The system unit provides for the installation of a power supply unit at the top of the case - then, choose any model with a horizontally located fan. Larger diameter means less noise (with the same cooling capacity).
The rotation speed should vary according to the internal temperature. When the power supply unit does not overheat - why do you need to turn the "valve" at all revolutions and annoy the user with noise? There are PSU models that completely stop their fan when the power consumption is less than 1/3 of the calculated one. Which is convenient.
The main thing in the PSU cooling system is its silence (or the complete absence of a fan, this also occurs). On the other hand, cooling is needed then to prevent overheating of parts (high power, in any case, entails heat generation). At high capacities, a fan is indispensable.
Note: the photo shows the result of modding (removing the standard slotted grill, installing a Noktua fan and a 120mm grill).
Connectors and cables
When buying and choosing, pay attention to the number of available connectors and the length of the wires coming from the power supply. Depending on the geometry of the case, you need to choose a power supply unit with a sufficient cable bundle in length. For standard ATX cases, a 40-45 cm bundle will suffice.
The power supply unit that works in a home and office computer has connectors:
This is the 24-pin power connector on the PC motherboard. Usually there are separate 20 and 4 contacts, but sometimes it is monolithic, 24-pin.
Processor power connector. Usually it is 4-pin, and only for very powerful processors 8 pins are used. You can choose the right power supply for your computer by focusing on the corresponding connector on the motherboard itself.
The connector for the power supply of the video card looks similar, and differs in that it is 6 or 8-pin.
Connectors (connectors) for powering SATA devices (hard drives, optical drives), four-pin Molex (for IDE), and for turning on the FDD (or card reader) are familiar to most users:
Note: the number of all additional connectors (SATA, MOLEX, FDD) must be sufficient to connect devices located inside the system unit.
Montage demontage
To dismantle the old power supply, disconnect its 220 Volt wire. Then, you need to wait 2-3 minutes, and only then start to work. Attention! Failure to do so may result in electrical injury.
The power supply unit in any PC is attached to the back wall with 4 screws (self-tapping screws). You can unscrew them only by disconnecting all internal connectors and plugs of the power supply (2 connectors of the motherboard, video cards, connectors for additional devices).
You can connect the power supply to the computer in the reverse order: first, we mount it into the case, securing it with screws, then we connect the connectors.
Note: When manipulating the power supply, the processor cooler may interfere. If it is possible to dismantle it, use this (put it in place - then, before turning it on).
Turning on the computer with a new power supply unit
Having supplied 220 Volt power to the new PSU, you do not need to turn on the computer right away. Wait 10-15 seconds at first: you will listen to see if there is anything “out of the ordinary” going on. If we hear a squeak, a ringing of throttles, we go and change the power supply under warranty. If you hear a repetitive "metallic" click - do not turn on the computer with such a power supply.
If in standby mode, the power supply "clicks" - this is the protection system. Disconnect such a power supply unit, disconnect its connectors (connectors). You can try to assemble the same thing again - if the problem repeats, we take the power supply to the service center (the unit itself may be faulty).
A computer with a working power supply unit turns on almost immediately when the “Power” button of the ATX case is pressed. An image should appear on the monitor - now you can continue working, but with a new power supply unit.
Modular cables and connectors
Many of the more powerful PSUs now use what is called a "modular" connection. Adding internal cables with corresponding mating connectors - occurs as needed. This is convenient because you no longer need to keep extra (unused) wires in the computer case, and besides, this way - there is less confusion. And the absence of unnecessary wires also improves the circulation of hot air. In modular power supplies, only cords with a connector for the motherboard / processor are made "non-removable".
Brands and manufacturers
All firms (manufacturers of power supplies for a computer) belong to one of 3 main groups:
- They completely produce their own products - brands such as Hipro, FSP, Enermax, Delta, also HEC, Seasonic.
- They manufacture products by shifting part of the manufacturing process to other companies - Corsair, Silverstone, Antec, Power & Cooling and Zalman.
- They resell ready-made blocks under their own brand (some - make "selection", some - not): Chiftec, Gigabyte, Cooler Master, OCZ, Thermaltake.
Each brand listed above can be safely recommended. On the Internet, in addition, there are many reviews and tests for "branded" power supplies, which can be used by the user.
Before buying a PSU, you should weigh it (just hold it in your hand). This will allow you to more or less understand what is inside him. Of course, this method is imprecise, but it allows you to immediately "dismiss" the obviously "cheap" power supply unit.
The mass of the power supply depends on the quality of the steel, the dimensions of the fan, and (most importantly): the number of chokes and the weight of the radiators inside. If the power supply unit lacks some inductance coils (or, for example, capacitors of reduced capacity), this indicates a "cheapening" of the electrical circuit: the power supply unit will weigh 700-900 grams. A good PSU (450-500W) usually weighs from 900 grams. up to 1.4 kg.
From the history
In the market of personal computers, that is, not only IBM-compatible, but in a more general sense of "computers", IBM initially went to standardize components (power supply unit, motherboard). The rest then began to "copy" it. All known form factors for IBM-compatible PC power supplies are based on any of the PSU models: PC / XT, PC / AT, and Model 30 PS / 2. All compatible PCs, one way or another, could use one of the three original standards developed by IBM. These standards were popular until 1996, and even later, the current ATX standard dates back to the physical layout of the PS / 2 Model 30.
The new form factor, that is, the ATX we know, was defined in 1995 by Intel (then an IBM partner), presenting the standard for the motherboard and power supply. The new standard has gained popularity since 1996, and manufacturers have gradually begun to move away from the outdated AT standard. ATX and some of the "offshoots" of the standard that followed, use non-AT connectors mat. boards (not only with additional voltages, but also signals that allow you to provide more power and additional capabilities).
All IBM standards provided for the physically the same connector that supplies power to the motherboard. To turn it on and off, to supply power to the computer, a toggle switch (or button) was used, breaking the wire with a voltage of 220 volts. Which was not very convenient (especially when disassembling / repairing a PC). Therefore, a new standard has appeared, which "does not allow" a voltage of more than 12 volts inside the system unit (inside the case).
It must be said that the power circuit itself (the principle of its construction), starting from the first PC XTs, has not received significant changes. The principle of energy conversion used in computer power supplies is called "pulsed" (a "constant" is made from an alternating voltage of 220 volts, then it is converted, reduced to lower values by a pulse method). The first power supplies for personal computers were rated at 60 W (XT), or say 100-120 W (AT 286). Simply, then the computer provided for the installation: 1-2 drives, one hard drive (and the processor itself - "consumed" very little).
Development prospects
800 watts, 900 watts, 1000 watts ... A PC power supply that delivers one kilowatt of energy to the load is no surprise. Of course, the price is significantly different (from "standard" boxes for 450-500 W), however, such a power supply unit provides a sufficient level of reliability (and - low noise level) even when fully loaded! Well, just a miracle.
If we calculate how much energy such a computer will consume from the outlet, it turns out that this is nothing more than the equivalent of an iron that is constantly turned on at full power. Such a good one, in terms of power - above average, heavy ...
Recently, with the transition to new technological processes for the production of "main" microcircuits for a computer (central processor, 3-D module), the movement has been just "opposite" - that is, a decrease in the total power while maintaining the same level of performance. Two years ago, an average 4-core "percent" consumed at least 90 W, now it is already 65 ("new", while - faster). In any case (both 2 years ago and now), the choice is up to the user.
Currently, they are practically not used.
- The −5 V voltage was used only by the ISA interface and due to the actual absence of this interface on modern motherboards, there is no −5 V wire in new power supplies.
- The -12 V voltage is only required for the full implementation of the RS-232 serial interface standard, so it is also often absent.
In most cases, a switching power supply is used, made according to a half-bridge (push-pull) scheme. Power supplies with energy-storing transformers (flyback circuit) are naturally limited in power by the dimensions of the transformer and therefore are used much less often.
Device (circuitry)
Switching computer power supply (ATX) with the cover removed: A - input diode rectifier, visible below inlet filter; B - input smoothing capacitors, the radiator is visible to the right high voltage transistors; C - pulse transformer, to the right you can see the low-voltage radiator diode rectifiers; D - group stabilization choke; E - output filter capacitors
A widespread switching power supply circuit consists of the following parts:
Input circuits
- Separate low-power power supply unit, issuing +5 V standby mat. board and +12 V for powering the converter microcircuit of the UPS itself. Usually it is made in the form of a flyback converter on discrete elements (either with group stabilization of output voltages through an optocoupler plus an adjustable Zener diode TL431 in the OS circuit, or linear stabilizers 7805/7812 at the output) or (in top models) on a TOPSwitch type microcircuit.
- Half-bridge converter on two bipolar transistors
- Converter control circuit and computer protection against over / under supply voltages, usually on a specialized microcircuit (TL494, UC3844, KA5800, SG6105, etc.).
- Pulse high-frequency transformer, which serves to form the required voltage ratings, as well as for galvanic isolation of circuits (input from output, and, if necessary, output from each other). The peak voltages at the output of the high frequency transformer are proportional to the input supply voltage and are much higher than the required output voltage.
- A feedback circuit that maintains a stable voltage at the output of the power supply.
- A PG (Power Good) voltage driver, usually on a separate op amp.
- Output rectifiers. Positive and negative voltages (5 and 12 V) use the same output windings of the transformer, with different directions of switching on the rectifier diodes. To reduce losses, at high current consumption, Schottky diodes with a low forward voltage drop are used as rectifiers.
- Output group stabilization choke. The choke smooths out the pulses by storing energy between pulses from the output rectifiers. Its second function is the redistribution of energy between the output voltage circuits. So, if through any channel the current consumption increases, which reduces the voltage in this circuit, the group stabilization choke, like a transformer, will reduce the voltage in other circuits. The feedback loop will detect a decrease in the output circuits, increase the total power supply, and restore the required voltage values.
- Output filter capacitors. Output capacitors, together with a group stabilization choke, integrates pulses, thereby obtaining the necessary voltage values that are significantly lower than the voltages from the transformer output
- One (on one line) or several (on several lines, usually +5 and +3.3) 10-25 Ohm pull-up resistors, to ensure safe idle operation.
Dignity such a power supply:
- Simple and time-tested circuitry with a satisfactory quality of stabilization of output voltages.
- High efficiency (65-70%). The main losses are due to transients, which last much less time than steady state.
- Small dimensions and weight, due to both less heat generation on the regulating element, and smaller dimensions of the transformer, due to the fact that the latter operates at a higher frequency.
- Less metal consumption, due to which powerful switching power supplies are cheaper than transformer ones, despite the greater complexity
- The ability to connect to the network of a wide range of voltages and frequencies, or even direct current. Thanks to this, it is possible to unify equipment produced for different countries of the world, and therefore to reduce its cost in mass production.
Flaws half-bridge bipolar transistor power supply:
Standards
AT (deprecated)
In power supplies for computers of the form factor, the power switch breaks the power circuit and is usually placed on the front panel of the case with separate wires; standby power supply with corresponding circuits is absent in principle. However, almost all AT + ATX motherboards had a power supply control output, and power supplies, at the same time, had an input that allowed an AT motherboard to control it (turn it on and off).
The AT power supply connects to the motherboard with two six-pin connectors that plug into one 12-pin connector on the motherboard. Multi-colored wires go to the connectors from the power supply, and the correct connection is when the contacts of the connectors with black wires converge in the center of the motherboard connector. The pinout of the AT connector on the motherboard is as follows:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| - | |||||||||||
| PG | empty | + 12V | -12V | general | general | general | general | -5V | + 5V | + 5V | + 5V |
ATX (modern)
On a 24-pin ATX connector, the last 4 pins can be removable to ensure compatibility with a 20-pin socket on the motherboard
The requirements for + 5VDC have been increased - now the PSU must deliver a current of at least 12 A (+3.3 VDC - 16.7 A, respectively, but the total power should not exceed 61 W) for a typical 160 W consumption system. An imbalance in the output power was revealed: before the main channel was +5 V, now the requirements for a minimum current of +12 V were dictated. The requirements were due to a further increase in the power of components (mainly video cards), whose requirements could not be met by the +5 V lines due to for very high currents in this line.
Power supply / power supply connectors
Pinout of SATA connectors
ATX PS 12V (P4 power connector)
One of two 6-pin AT power connectors
- 20-pin main power connector + 12V1DCV used with the first ATX motherboards, before PCI-Express motherboards.
| Color | Signal | Contact | Contact | Signal | Color |
|---|---|---|---|---|---|
| Orange | +3.3 V | 1 | 13 | +3.3 V | Orange |
| +3.3 V sense | Brown | ||||
| Orange | +3.3 V | 2 | 14 | −12 V | Blue |
| Black | Land | 3 | 15 | Land | Black |
| Red | +5 V | 4 | 16 | Power on | Green |
| Black | Land | 5 | 17 | Land | Black |
| Red | +5 V | 6 | 18 | Land | Black |
| Black | Land | 7 | 19 | Land | Black |
| Grey | Power good | 8 | 20 | −5 V | White |
| Violet | +5 VSB | 9 | 21 | +5 V | Red |
| Yellow | +12 V | 10 | 22 | +5 V | Red |
| Yellow | +12 V | 11 | 23 | +5 V | Red |
| Orange | +3.3 V | 12 | 24 | Land | Black |
| Pin 20 (and white wire) is used to provide −5 VDC in ATX and ATX12V versions up to 1.2. This voltage is not mandatory already in version 1.2 and is completely absent in versions 1.3 and later. | |||||
| In the 20-pin version, the right-hand pins are numbered 11 to 20. | |||||
| Orange +3.3 VDC wire and brown +3.3 V sense wire connected to pin 13 are 18 AWG thick; all others - 22 AWG | |||||
Also on the power supply unit are located:
Efficiency - "80 PLUS"
| External images | |
|---|---|
| Power supply drawing FSP600-80GLN | |
| Assembly drawing of power supply unit FSP600-80GLN in PDF format | |
Computer power supply manufacturers
- Cooler master
- Corsair
see also
Notes (edit)
- to comply with the requirements of the legislation of countries on electromagnetic radiation, in Russia - the requirements of SanPiN 2.2.4.1191-03 2.2.4.1191-03.htm “Electromagnetic fields in industrial conditions, at workplaces. Sanitary and Epidemiological Rules and Regulations "
- B.Yu. Semenov Power electronics: from simple to complex. - M .: SOLOMON-Press, 2005 .-- 415 p. - (Engineer's Library).
- At +12 VDC peak load, the +12 VDC output voltage range may fluctuate by ± 10.
- Minimum voltage level 11.0 VDC during peak load at +12 V2DC.
- The shutter speed in the range is required for the main power connector of the motherboard and the S-ATA power connector.
- The total power on the +3.3 VDC and +5 VDC lines should not exceed 61 W
- The total power on the +3.3 VDC and +5 VDC lines should not exceed 63 W
- The total power on the +3.3 VDC and +5 VDC lines should not exceed 80 W
Hello again, dear readers! Let's talk how to choose a power supply.
As you can see from the title of our next " Sis.Adminskaya»Notes, today we will talk about the power supply (hereinafter - BP). You ask: "why did we decide to devote an entire article to such seemingly, an insignificant element of a personal computer (PC)? "We answer: - all because not all users (or rather, a minority) pay due attention to the healthy diet of their" pi-si ".
I think you will agree with me if I say that power supply units are bought from us on the basis of the "residual principle", i.e. what have I not bought yet? Oh yes - the power supply. Okay (how much do we have left?) - I'll take this one on the left " noname"(Unknown manufacturer) on the top shelf. Is that so, admit it?
But this is not the kind of thing that is worth saving on (because your entire heaped PC can turn into a pile of gadgets in one second), and today I will tell you why.
By the way, this is a continuation of the cycle by selection criteria, ie articles like "”, "", "” and all that different from the "Selection criteria" tag.
Go.
What is it and why is it needed - introductory
We will start with the "golden" rule for choosing / buying a BP, which says: "Stingy, pays twice!" (and if stingy, also stupid, then three times :-)). Remember it, after all, it is a good power supply that is the key to stable and durable computer operation. Buying a cheap model, you run the risk of getting burned, please note, in the literal sense.
In order to make a conscious and correct choice, let's go over the theory (where can we go without it), and then “hit” practice and tell about the rules of choice.
So, the power supply unit, also known as a "blockchain", it is also a "back-up" (and a bunch of other names) is responsible for ensuring stable and correct power supply (i.e. characteristics not must exceed the permissible limits for various loads). In addition, the reliability and safety of information on internal drives (in the event of a power failure, power surges, etc.) and how long the components of your "bosom" friend will work on depend on it.
Everyone knows that a computer is connected to a standard electrical outlet, but (not everyone knows) that its components cannot receive energy directly from the mains, for two reasons.
First, the network uses alternating current, while the computer components require direct current. Therefore, one of the tasks of the power supply is to "rectify" the current.
Secondly, different components of a computer require different supply voltages to operate, and some require several lines with different voltages at once. Thus, the power supply unit, among many other things, provides each device with a current with the necessary parameters and for this it has several power lines (see image).
The main power circuits are voltage lines: + 3.3 B, + 5 B and + 12 B. Moreover, the higher the voltage, the more power is transmitted through these circuits. The most powerful consumers of energy, such as a video card, central processor and northbridge, use the + lines 5 B and + 12 B. The power connectors of hard drives and optical drives are supplied with voltage +5 B, for electronics and +12 B for the motor. Negative supply voltages −5 In and −12 V allow small currents and are often not used by the motherboard.
What do we need from a PSU? Basic parameters for choice
We figured out that the power supply is the only source of electricity for all PC components, now we move on to the characteristics (the current supplied to them), on which the stability of the functioning of the entire system directly depends.
So, in general (from this), we do not need so much, namely, that:
- Gave a stable and accurate voltage at the outputs 12 /5 /3.3 volt. The output is not absolutely constant voltage ( U), and constant / intermittent (ideal when U- can "walk" on 0.5 To the maximum);
- Had a good line dividing system 220 In and your PC (it is bad systems that lead to soot on the boards)
- Its elements were made of high-quality materials, because a common cause of death of a power supply is cheap capacitors with a short service life, poor cooling (and excessive heating) of the power supply components, as well as the lack of fuses and other important pieces
If the above reasons and needs are not met, many cheap and medium-sized power supplies "dump" out of the nominal values by 2 volts and this is with a load of only 70 % of par! This can lead to incomprehensible computer overloads "all of a sudden", freezes, in the middle of a responsible work, as well as, say, to partial instability of devices (the monitor goes out).
What do users say at the same time?
Naturally, they do not blame their choice and economy, but the fact that the "Curve WindoZ" or "Bill Gates Co3 .." (c), although neither one nor the other is not the reason.
However, we digress a little from the topic, and meanwhile have already considered the main "electrical" parameters, although there are also many technical ones.
Let's deal with them.
Power Supply Specifications - power
So, the main characteristic of a PSU is its power. It must be at least equal to total power consumed by components PC with the maximum computational load, and with a normal choice, that is, with an adequate buyer, it is good if it exceeds this indicator by 100 W or more. Otherwise, the computer may turn off during peak load, reboot, or, much worse, the power supply will burn out, and if, when it burns out, it supplies (to the motherboard, hard drives, DVD ± RW) high voltage, then it will not go to the “other world” one, but necessarily in a friendly campaign of these devices (frequent practice).
You can independently make approximate calculations of the power required to power your computer. Each component in the system consumes a certain amount of power, adding up the power consumption values for all components inside the PC case, and adding 20 % in reserve, you will receive the desired power of the power supply. In addition, on the Internet you can find special "calculator programs" for calculations of this kind.
One of these programs is free, Russian-language and quite adequate :-)
As already mentioned and you yourself understood, this calculator allows you to calculate the power supply for a PC of any configuration. The program interface is simple and straightforward, so you can easily figure it out and calculate the required power.
Efficiency. Efficiency
High power alone does not guarantee quality performance. In addition to it, other parameters are also important, for example, efficiency. This indicator indicates what proportion of the energy consumed by the power supply unit from the electrical network goes to the computer components. The higher the efficiency, the less the power supply heats up (and there is no need for enhanced cooling with a noisy fan), i.e. more efficiently converts energy from an electrical outlet into declared watts and, of course, the less energy is wasted on heating. For example, if it is 60 %, then 40 % of your energy hovers around the room (catch it :-)).
The "efficiency" of the power supply unit is assessed by its own system of medals - the standard " 80 PLUS».
This standard implies several levels of effectiveness: Platinum, Gold, Silver and Bronze, and the specifications of each of them have their own set of requirements. Of course, the power supplies " 80 PLUS Platinum" or " 80 PLUS Gold"Will be more efficient (efficiency 90 % and higher) than their regular counterparts, but they also cost more. Therefore, here it is better to use the rule - choose a model with certification “ 80 PLUS", And select the level of the" medal "based on your budget (but not lower than bronze).
Among other things, information on all modules of the standard " 80 PLUS", Available on the website of the organization. Manufacturers certify knowingly high-quality models using it, since power supplies with cheap circuitry simply will not pass the criteria. It is for this reason that this certificate is an additional guarantee of quality, that is, look for a power supply unit with it.
Power Factor Correction
The module PFC, which in Russian means "power factor correction". Module PFC- a special element designed for power factor correction and aimed at protecting the network. PFC conditionally divided into active (Active) and passive (Passive).
We recommend buying power supplies with PFC(they allow you to achieve a high level of efficiency - up to 95 %), and active (Active), because APFC, additionally equalizes the input voltage, which in turn allows stable operation of all devices that output an analog signal from the computer.
Note that models with APFC slightly more expensive than their passive cousins, but the difference in efficiency will later be reflected in your electricity bills.
Maximum current on individual lines
The total power of the power supply is the sum of the powers that it can provide on the individual power lines. If the load on one of them exceeds the permissible limit, then the system will lose stability, even if the total power consumption is far from the nominal value. In total (as you already know) there are three lines 12V; 5B and 3.3V; a little more about them.
12 -volt is supplied, first of all, to powerful consumers of electricity - a video card and a central processor. The power supply should provide as much power as possible on this line. To power high-performance video cards, two 12 -volt lines. Lines with tension 5 It supplies power to the motherboard, hard drives and optical drives of the PC. Lines on 3.3 B, go only to the motherboard and provide power to the RAM.
It should also be said that the load on the lines in modern systems, as a rule, is uneven and here it should be borne in mind that the "hardest" of all has 12 -volt channel, especially in configurations with powerful video cards, but about the lines 5B/3.3V also do not forget, their total current should not exceed 30 % of the total power supply current.
Dimensions (edit)
When specifying the dimensions of the PSU, manufacturers, as a rule, limit themselves to the designation of the form factor, which must meet the standard ATX 2.X... See this on the power supply itself (arrow 1 in the image) or on the documentation that came with it. Also, when buying, we advise you to compare its dimensions with the dimensions of the "seat". Pay attention, if there is an inscription on the case “ noise killer»(Arrow 2 in the image), the fan rotates as slowly as possible, which reduces the sound level. The rotation speed is regulated by a special temperature sensor.
Old power supply (standard AT), which turns the computer on and off with a regular power switch, is far from the best option. Now its purchase can be justified only by the fact that you have an "ancient" car at home, into which it is physically impossible to insert a more modern module.
Better to choose ATX- a device that only works after a command from the motherboard. This technology makes it possible to remove the high-voltage wire from the unit and improve safety. Even if the block ATX burns, the likelihood that something else will suffer is much lower. In turn ATX the standard has several different modifications. Version ATX 2.03 , is produced for powerful computers with high energy consumption.
Cable-managment system. All about "wires"
This name summarizes the way the cables are connected to the power supply. The essence of the technology is that only the necessary cables that come with the delivery set are connected to the module.
For example, the unit has many cables that allow you to connect, say, from 3 before 5 hard drives, up to 2 -3 video cards, etc. But usually a computer has a maximum of three hard drives and one video card. In this case, it turns out that all these unused cables simply hang in the system unit and only interfere with cooling, because obstruct air circulation.
The modular cable connection technology allows, as needed, to connect only the cables that are needed at the moment, and leave unnecessary ones “out”. For such modules, only the main cables are non-removable, for example, for powering the motherboard, processor, and one cable for additional power to the video card.
The power supply unit must not only provide the required power, but also correctly supply voltage to all components, and this requires the appropriate connectors.
For example, there must be at least six pieces (although you can expand it with a special splitter, but you have to buy it). A computer with two hard drives and a pair of optical drives already uses four of these connectors, and Molex other devices can also be connected - for example, case fans and "ancient" video cards with an interface AGP. The power cables must be long enough to reach all required connectors. Another important additional option, the presence of which is highly desirable, is the braiding of the cable.
It, firstly, greatly simplifies the installation of a computer and the connection of new devices, and secondly, it avoids clamps and breaks of cables due to entanglement.
Cooling and noise
During operation, the components of the power supply get very hot and require increased cooling. For this, fans (built into its case) and radiators are used. Most use one size fan 80 or 120 mm (which are quite noisy), and the higher the power supply unit, the more intense air flow is required in order to cool it. To reduce the noise level in high-quality systems, fan speed control circuits are used in accordance with the temperature inside the block module.
Some models allow the user to determine the fan speed by himself using a regulator on the rear wall, there are also models that continue to "pump" air some time after the computer is turned off. This allows the computer components to cool down faster after work.
Safety
High-quality power supplies are equipped with various systems to protect against voltage surges, overloads, overheating and short circuits. These features not only protect the power supply, but other components of the computer as well.
Note that the presence of such systems in the power supply does not exclude the need to use uninterruptible power supplies and surge protectors.
MTBF
As a rule, the guarantee is N The number of hours of work is one of the signs of a quality product. Yes, such models are somewhat more expensive, but the manufacturer determines the guaranteed operating time of the device. The best option here is the term 3 -5 years. Information about this is contained in the instruction manual, as well as duplicated on the packaging.
Manufacturer and weight
When buying any good thing, we definitely look at the brand / manufacturer - BP is no exception. In my eyes, the company has recommended itself the best Chieftech(model Chieftec or its older version Chieftec- divine, I know from my own experience and the experience of hundreds of friends). Perhaps you should pay attention to: InWin, Seasonic, FSP, Zalman etc., so take a closer look at them. Buy noname strongly and irrevocably not recommended.
It is also worth knowing that a high-quality power supply should weigh on average from 2 before 2.5 kg (so you can safely take the scales with you and measure its weight). Do not take the light one as a "fluff", because there is a possibility that the manufacturer saved on the filling (transformers, radiator, etc.).
In order to somehow reward you for the fact that you yourself wanted to understand all the intricacies of such a difficult device and have already passed a good half of the article, I will tell you about one more useful trick (which is worth paying attention to), which few people know about.
All models sold in the foreign and Russian market must be certified Underwriters Laboratories), in the form of a number UL... Power supplies are laboratory certified UL, after which they are assigned a number. The most interesting thing is that this number always indicates the real manufacturer, regardless of the brand under which the latter is sold. And in the online database UL You can always find by the manufacturer number and see the parameters of the power supply. To find a number UL, you do not need to open the module itself. Typically, this number is located under the logo UL and starts with the letter E.
When you find the number UL on the label, the matter is small: you need to refer to and enter the number in the paragraph " UL File Number". Then you need to press the " Search"And that's it.
You will receive information about the manufacturer, as well as a link to a document that contains the main characteristics of the power supply, including the maximum load on the lines. Lack of number UL speaks of the questionable quality of the product. Such power supplies should not be taken.
The practice of choosing a power supply. We read the label.
In general, the theory is over (:-)), now a few words about practice ..
Here you come to a shop and want to choose a high-quality power supply yourself. What to look for and what to do?
Well, the most important thing you have to do is turn on my head and remember everything that you already know. Also, do not ask the advice of a sales assistant (as a rule, only yesterday took up the position), but it is better to pick up the device, turn it around and find its "technical passport" (which, by the way, is present on every power supply unit) in the form of this such a sticker.
So, we deal with this (sticker).
How to choose a power supply - label nuances - steps
The main parameter on it is the so-called Combined Power / Combined Wattage... This is the ultimate total power for all existing power lines. In addition, the limiting power is also important for individual lines. If there is not enough power on a line to "feed" the devices connected to it, then these components may work unstable, even if the total power is sufficient.
As a rule, not all power supplies indicate the maximum power for individual lines, but all of them indicate the current strength. Using this parameter, it is easy to calculate the power: for this you need to multiply the current by the voltage in the corresponding line.
The power of the power supply can be calculated by adding the powers on its individual lines (arrow 1, in the image). They, in turn, are determined by multiplying the voltage on the corresponding line by the maximum current on it (arrow 2, in the image).
Step two.
Remember the number UL(on the sticker) and are looking for reliable information about the manufacturer.
Step three.
We are looking for an inscription of compliance with the standard “ 80
PLUS»And determine the efficiency.
Step four.
We estimate the weight in an experienced (scales) or "manual" (:-)) method.
Actually, this is where the visual inspection is over (the label has been examined), the necessary parameters have been identified - we can safely take our future power supply.
So, buy - bought, but now you still need to connect correctly. There is nothing complicated in this and you yourself can do it perfectly, having previously familiarized yourself with the "topology" of the connectors (ie what / where to connect). And to make it easier to comprehend this, the following conditional schemes will help you.
- A cable with this connector connects to the motherboard. Depending on the type of board, it is equipped with 20 or 24 contacts;
- Modern processors usually require additional power. A separate cable from the power supply unit is intended for this;
- Powerful graphics cards also require additional power. For this, one or two connectors are used with 6 or 8 contacts;
- Disk devices with interface IDE and case fans are connected to the power supply 4 -pin type connectors Molex;
- Hard drives and optical drives with interface SATA use a different type of connectors to receive power
That's all, we figured out the connection.
You see, it's not so difficult if you know the topology of the connectors and the basic connection rules, and you now know them.
So, bend your fingers, now you can not only choose the "correct" power supply unit, but also connect it, and therefore, breathe life into your "pieces of iron" (:-)).
Thus, you have moved from the level "who should I ask and should I call a specialist?" to a qualitatively new level “why! I'll do everything myself. " Please accept my congratulations!
And in the end, I will summarize everything that has been said here (and a lot has been said here, believe me) so that everything will finally be placed on the shelves with you. So, when buying a PSU, you should always remember that:
- Sufficient power. Choose a power supply with a power reserve (for 10 -30 % more than the total consumption of all components);
- Efficiency not less 80-85 %;
- Sufficient power along the lines 12 B, for powerful consumers;
- Line Power Ratio +5 B + 3.3 The total power must not be greater than 3 To 10 (30% );
- Certification " 80 PLUS", preferably above Bronze;
- Active module PFC(Power Factor Correction);
- Compliance with the standard ATX 2.X.;
- System Cable-managment- modular cable connection;
- Surge protection system;
- Well-known manufacturer ( Cooler Master, Enermax, Chieftec, FSP, OCZ, Zalman);
- Large weight;
- Good cooling.
Follow these simple tips and you won't need a fire extinguisher :-)
Where is the best place to buy a power supply?
- , - for those who are not afraid to buy abroad and save money. There are many, several popular brands, and in general a pleasant store, where there are permanent and so on;
- , - perhaps the best choice in terms of price-quality ratio SSD(and not only). Quite reasonable prices, although the assortment is not always ideal in terms of variety. The key advantage is the guarantee that really allows for 14 days to change the product without any questions, and in case of warranty problems, the store will take your side and help you solve any problems. The author of the site has been using it for years 10 minimum (since the days when they were part Ultra Electoronics), which advises you too;
- , - one of the oldest stores on the market, as a company exists somewhere on the order 20 years. Decent selection, average prices and one of the most user-friendly sites. All in all, it's a pleasure to work with.
The choice is traditionally yours. Of course, everyone's out there Yandex Market"Nobody canceled it, but from good stores I would recommend these very ones, and not any other large chains there (which are often not just expensive, but flawed in terms of quality of service, warranty, etc.).
Afterword
That's all! I hope you learned a lot (and who knew - remembered) from this material and now the choice and purchase of the "correct" power supply will not cause you the slightest difficulty, moreover, now you will become a "guru" on these issues, for most of your brothers in "pieces of iron" :-).
Until next time, stay tuned to the IT wave " Sysadmin Notes", Don't switch! ;)
If you have questions, additions, and other differences, then comments at your service.
PS: Thanks to team member 25 FRAME for the existence of this article
Transformer PSU
The classic power supply unit is a transformer power supply unit. In general, it consists of a step-down transformer or autotransformer, in which the primary winding is designed for the mains voltage. Then a rectifier is installed that converts alternating voltage into direct voltage (pulsating unidirectional). In most cases, the rectifier consists of one diode (half-wave rectifier) or four diodes forming a diode bridge (full-wave rectifier). Other circuits are sometimes used, for example, in voltage doubling rectifiers. After the rectifier, a filter is installed to smooth out oscillations (pulsations). Usually it is just a large capacitor.
Also, the circuit can be equipped with filters for high-frequency interference, bursts, short-circuit protection, voltage and current stabilizers.
Transformer dimensions
There is a formula that can be easily deduced from the basic laws of electrical engineering (and even Maxwell's equations):
(1 / n) ~ f * S * B
where n is the number of turns per volt (on the left side of the formula there is the EMF of one turn, which is the derivative of the magnetic flux according to Maxwell's equation, the flux is something in the form sin (f * t), in the derivative f is placed outside the parenthesis), f - frequency of alternating voltage, S is the cross-sectional area of the magnetic circuit, B is the induction of the magnetic field in it. The formula describes the amplitude B, not the instantaneous value.
The value of B is in practice limited from above by the occurrence of hysteresis in the core, which leads to magnetization reversal losses and overheating of the transformer.
Assuming f is the mains frequency (50 Hz), then the only two parameters available to choose when designing a transformer are S and n. In practice, the accepted heuristic is n = (from 55 to 70) / S in cm ^ 2.
An increase in S means an increase in the size and weight of the transformer. If we go along the path of reducing S, then this means an increase in n, which in a small transformer means a decrease in the wire cross-section (otherwise the winding will not fit on the core).
An increase in n and a decrease in the cross-section means a strong increase in the active resistance of the winding. In low-power transformers, where the current through the winding is small, this can be neglected, but with increasing power, the current through the winding increases and, with a high resistance of the winding, dissipates significant thermal power on it, which is unacceptable.
The above considerations lead to the fact that at a frequency of 50 Hz, a large (from tens of watts) power transformer can be successfully implemented only as a device of large size and weight (along the path of increasing S and wire cross-section with decreasing n).
Therefore, in modern power supplies, they go along a different path, namely, along the path of increasing f, i.e. the transition to switching power supplies. Such power supplies are several times lighter (and the bulk of the weight falls on the shielding cage) and are much smaller in size than the classic ones. In addition, they are not demanding on the input voltage and frequency.
Advantages of transformer power supplies
- Simplicity of design
- Element base availability
- Lack of generated radio interference (as opposed to pulse, which creates interference due to harmonic components)
Disadvantages of transformer PSUs
- Large weight and dimensions, especially at high power
- Metal consumption
- The trade-off between efficiency reduction and output voltage stability: A stabilizer that introduces additional losses is required to ensure a stable voltage.
Pulse power supplies
Switching power supplies are an inverter system. In switching power supplies, the AC input voltage is first rectified. The resulting constant voltage is converted into rectangular pulses of increased frequency and a certain duty cycle, either fed to the transformer (in the case of pulsed power supplies with galvanic isolation from the mains) or directly to the output low-pass filter (in pulsed power supplies without galvanic isolation). In pulsed power supplies, small-sized transformers can be used - this is due to the fact that with an increase in frequency, the efficiency of the transformer increases and the requirements for the dimensions (cross-section) of the core required to transmit the equivalent power decrease. In most cases, such a core can be made of ferromagnetic materials, in contrast to the cores of low frequency transformers, for which electrical steel is used.
In switching power supplies, voltage stabilization is provided through negative feedback. Feedback allows the output voltage to be kept at a relatively constant level regardless of input voltage fluctuations and load. Feedback can be organized in a number of ways. In the case of switching power supplies with galvanic isolation from the mains, the most common methods are using communication through one of the output windings of the transformer or using an optocoupler. Depending on the value of the feedback signal (depending on the output voltage), the duty cycle of the pulses at the output of the PWM controller changes. If isolation is not required, a simple resistive voltage divider is usually used. Thus, the power supply maintains a stable output voltage.
Advantages of impulse power supplies
Switching stabilizers comparable in terms of output power to linear stabilizers have the following main advantages:
- lighter because smaller transformers can be used with higher frequency for the same transmitted power. The mass of linear stabilizers consists mainly of powerful heavy low-frequency power transformers and powerful radiators of power elements operating in a linear mode;
- significantly higher efficiency (up to 90-98%) due to the fact that the main losses in switching stabilizers are associated with transients at the moments of switching the key element. Since most of the time the key elements are in one of the stable states (i.e., either on or off), energy losses are minimal;
- lower cost due to the mass production of a unified element base and the development of key high-power transistors. In addition, it should be noted that the cost of pulse transformers is significantly lower with comparable transmitted power, and the possibility of using less powerful power elements, since their mode of operation is key;
- reliability comparable to linear stabilizers. (Power supplies for computers, office equipment, household appliances are almost exclusively impulse).
- wide range of supply voltage and frequency, unattainable for a comparable in price linear. In practice, this means the possibility of using the same pulsed power supply unit for wearable digital electronics in different countries of the world - Russia / USA / England, which are very different in voltage and frequency in standard sockets.
- the presence in most modern power supplies of built-in protection circuits against various unforeseen situations, for example, against short circuits and against no load at the output.
Disadvantages of pulse power supplies
- Operation of the main part of the circuit without galvanic isolation from the network, which, in particular, makes it somewhat difficult to repair such power supplies;
- Without exception, all switching power supplies are a source of high-frequency interference, since this is due to the very principle of their operation. Therefore, it is required to take additional measures of interference suppression, which often do not allow to eliminate the interference completely. In this regard, it is often unacceptable to use pulsed power supplies for some types of equipment.
- In distributed power supply systems: the effect of harmonics in multiples of three. In the presence of effectively operating power factor correctors and filters in the input circuits, this disadvantage is usually not relevant.
Greetings, dear readers. I faced such a problem: recently my computer began to slow down. And this coincided with a drop in voltage in the electrical network. And I noticed this by the glow of the lighting lamps. So I immediately discarded all suspicions of viruses and other problems.
It's just that my old power supply unit did not cope, it did not have enough strength to pull the voltage to the desired level. This is where the problems with the system started. And in this article, I will share with you some thoughts on power supplies in your computer.
It would seem that a small component of the system unit (this is not a video card), why devote an entire article to it? It's simple: many people do not respect the power source of their PC with due respect, which leads to unpleasant consequences. Therefore, let's figure out why you need a power supply in your computer and how to choose it correctly.
What is a power supply unit and what is it used for
The power supply unit (aka PSU) is a power source in, which is responsible for providing energy to the remaining components. The durability and stability of the entire system largely depends on the power supply unit. In addition, the computer power supply prevents the loss of information from the personal computer by preventing power surges.
I am sure that every person who is in the slightest degree familiar with the technique knows that it works from an outlet. However, not every user is aware that the components of the system cannot receive energy directly.
This is how we smoothly approached the most interesting thing: what is a power supply unit for a PC for? For two reasons:
- Firstly, the current in the mains is variable, which is very "disliked" by computers. The power supply makes the current constant, correcting the situation;
- Secondly, each component of a PC, and indeed a laptop, requires a different voltage. And again the power supply unit comes to the rescue, giving the necessary current to the processor and video card.
Choosing a power supply for your computer
Of course, it is much more interesting to choose an expensive video card or an external one for your “friend” than a power supply unit. Therefore, this component is often bought not in the first place, and so to speak, with the last money. However, you should understand: a model with low power may not be able to handle a modern video card. But don't be discouraged - the PSU doesn't cost that much. So, I'll tell you what to look for when buying, and you will already decide which one to choose.
Power
The first thing to pay attention to is the power of the model. It should be chosen based on personal needs and the rest of the "hardware". If you have an office-type personal computer (weak components, tasks are reduced to working with text editors and surfing the Web), then a 300 - 400 W model is enough. They are quite cheap, so they are the most popular on the market. But fans of "drive" in modern games will have to fork out for a more expensive power supply unit, which can pull all your "hardware". It doesn't hurt to buy it too.
How do you know how much power you need? Fortunately for users, today the Internet is full of services that will help you make a calculation to determine the required power for your components. You can calculate it yourself, it's not so difficult. It is enough to add up the power of all components of your system: motherboard (50-100 watts); processor (65-125 watts); video card (50-200 watts); hard disk (12-25 watts); RAM (2-5 watts). It is recommended to add 30% to the resulting number in case of overloads. Go for it!
Efficiency
This very important point is often overlooked by novice users. But it should be. The durability of the power supply, as well as power consumption, depends on the efficiency. The fact is that the power supply unit accepts a certain amount of energy, but gives away less, losing part. Manufacturers have solved this problem by dividing the models into classes: expensive - more efficient, cheaper - please put up with the loss of energy. This classification is carried out using special stickers: Bronze, Silver, Gold, Platinum (from best to worst).
Connectors
So, before connecting the power supply unit is still far away - we are determined with the connectors. There can be no tips here, especially if you have already selected the main components for the system. Choose a set of connectors based on the rest of the hardware. If you decide to pay more attention to the unit, having bought it in the first place, then take a closer look at the latest models that received modern ports. Of course, if finances permit.
The standard set of connectors today looks like this: motherboard connector (24-pin), processor power (4-pin), optical drives and hard drives (15-pin SATA), video card power (at least one 6-pin). Please note that if you have a very old system, this set of connectors may not work. And finding a power supply unit for outdated components is very problematic.
Protection
Faced with various glitches and problems, manufacturers have gradually endowed their product with all kinds of protection from adverse influences. Today the list of such functions includes dozens of items. Find on the box or in the attached instructions what the model is protected from (power surges, malfunctions, and so on). More features are better.
Noise and cooling
Yes, these characteristics are interrelated. A low-power PSU does not get very hot, so its cooling system also consists of a small fan. When buying a model for a gaming system, you can be sure that it will heat up no worse than a stove (with the exception of expensive blocks from well-known manufacturers). You can't get away from the noise that the powerful PSU emits, along with the rest of the components.
Modern manufacturers offer models with fans of different sizes, the most common is 120 mm. There are also blocks of 80 mm and 140 mm. In the first version - strong noise and poor cooling, in the second - a difficult replacement of the fan in case of failure.
It's all. There are, of course, a number of other parameters that experts turn to when choosing a power supply unit, but they should be taken into account if you are buying a model for complex (rare) tasks. In other cases - building a home PC - and our advice will be enough.
Prices
Today, manufacturers offer a huge number of power supplies at a variety of prices. Want to save money? No question, models for an office system can be bought in the region of $ 25-35. Add another $ 25 and we have a decent 700 Watt PSU. Models for powerful gaming systems can cost $ 250 and up.
We connect
Buy - bought, but not to be on the shelf. Now you need to connect it. The easiest option, if you do not understand computers at all, is a friend who will do everything in a few minutes. And if you yourself want to assemble your system, then wait for a new article in which we will analyze in detail the connection of the power supply. In fact, there is nothing complicated. The main thing is not to try to shove the cable into the connector if it does not want to fit.
Read other interesting blog articles, share with your friends. Good luck!
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