Calculate the power of the power supply. Calculation of the required power or How to choose a Power Supply

The task of the computer power supply is to turn 220 volts AC into three different DC voltages. The incoming mains voltage constantly fluctuates slightly, and the load on the video card, central processor and other components often “jumps” very strongly. In this case, the power supply is required to constantly and accurately maintain the desired voltage.

The power supply is one of the key components that affect the security of the system as a whole.: if there is any defect, the currents passing through it can damage the components connected to it and even cause a fire. In general, there are plenty of arguments for a serious approach to choosing a high-quality PSU.

A good PSU should operate as efficiently as possible (i.e. with low heat loss). It is also undesirable that its fans are very noisy. And the electrical elements must be completely silent at low load (the noise of the chokes should not be heard).

Power

Depending on the components, computers can consume power from a few watts to several kilowatts. The power supply must be designed to handle the maximum load, and it is desirable to have reserves - only in this case it will work efficiently and quietly.

The optimal PSU power can be calculated by the sum of TDP(thermal package) of the processor and video card, multiplied by 1.5. So, for a Core i5-8600 processor (TDP 65 watts) and an AMD Radeon RX 560 video card (TDP 75 watts), a power supply unit with a capacity of at least 450 watts is suitable. A 450-watt unit would be loaded by about 50%, a 750-watt unit by 30%. For an accurate calculation, use the power supply wattage calculator: bequiet.com/en/psucalculator.

Power supply for office PC

If you are building a simple PC for office tasks, then it is not at all necessary to buy a powerful power supply. Enough and 300 watts. But you still need to have a stock. After all, you can work not only in Word, but also edit graphics and even build 3D models. For these purposes, a 500 W PSU is perfect, you won’t feel much savings when buying a device with a lower return (if you take high-quality ones).

Depending on the components used in them and the cooling system, their price varies from 2,000 to 7,000 rubles. In order for your PC to serve for a long time, we recommend not to save much and opt for a power supply from a well-known brand, for example, Thermaltake TR2 S 500W, which costs about 3,200 rubles.

It has a very quiet cooler, high-quality elastic braided wires, and delivers 75W on the 5V line and 420W on the +12V line.

Efficiency

So, a good power supply provides the maximum possible power consumption of all PC components. In order to be able to evaluate the efficiency of the power supply even before purchase, manufacturers certify them according to the 80 Plus energy saving standard with additional levels of Bronze, Silver, Gold, Platinum and the very rare Titan.

Each power supply generates heat that, in rare models with a passive cooling system, is only removed by a heatsink, requiring precise planning and constant optimal environmental conditions. For users who are extremely sensitive to noise, we recommend a power supply with a hybrid cooling system, such as Corsair RM550x, costing about 8,000 rubles.

Corsair RM550x notable in that its fan only turns on when the load exceeds 40% or the temperature rises. This ensures stable continuous operation under all circumstances. For other users, we recommend conventional PSUs with an active cooling system - for example, be quiet Straight Power 10. Its fan runs almost silently under light load. Noise only appears when full power is required.

Expensive capacitors last longer

The first step to high quality is the choice of well-known manufacturers: be quiet!, Cooler Master, Corsair, Enermax, Thermaltake Xilence and others. As for equipment, when choosing a power supply, you should pay attention to the presence of all the necessary plugs - affordable models often do without a power connector for SATA devices, and some may even comply with the outdated standard.

Also check the exact number of 12V plugs (6-pin or 8-pin) for your graphics card. A modern modular connection technology Cable management allows you to connect only the cables you need to the PSU and not mess up the case.

Expensive capacitors of top PSU models withstand high temperatures (for example, not 85 ° C, but 105 ° C), so they last longer. Manufacturers can anticipate this fact quite accurately. Long-lasting power supplies can be searched among models with a five-year warranty. For example, CoolerMaster G650M, with a power of 650 watts and a cost of about 5,600 rubles.

A photo: manufacturing companies

For a computer, it directly depends on what components are installed on it. If the power is not large enough, the system simply will not start.

Criteria for selecting a power supply

First you need to review the installed equipment: motherboard, video card, processor, processor cooler, hard drive (if there is one) and disk drive. Next, measure the power consumption of each of them. How to calculate the power of the power supply if the video card and processor support overclocking? It's simple - you need to measure the power consumption of these components in the overclocking state.

Of course, there is a more simplified version - this is an online calculator. To use it, you will need the Internet and knowledge of your own equipment. The data of the components are entered in the required fields, and the calculator calculates the power supply for the PC.

If the user intends to install additional equipment, such as another cooler or hard drive, then the calculations will have to be made based on additional data.

The first step to how to calculate the power supply for a computer is to calculate the efficiency of the unit itself. Most often it happens that a block of 500 watts can produce no more than 450 watts. In this case, you need to pay attention to the numbers on the block itself: the largest value indicates the total power. If you add up the total load of the PC and the temperature, you get an approximate calculation of the power of the power supply for the computer.

Power consumption of components

The second item is a cooler that cools the processor. If the power dissipation does not exceed 45 watts, then such a cooler is only suitable for office computers. Multimedia PCs draw up to 65 watts, and the average gaming PC will require cooling, with a power dissipation of 65 to 80 watts. Those who are building the most powerful gaming or professional PC should expect a cooler with a capacity of over 120 watts.

The third point is the most inconsistent - this is the video card. Many GPUs are able to work without additional power, but such cards are not gaming. Modern video cards require an additional power supply of at least 300 watts. What power each video card has is indicated in the description of the GPU itself. You also need to consider the possibility of overclocking the graphics card - this is also an important variable.

Internal burners consume, on average, no more than 30 watts, the same power consumption has an internal hard drive.

The last item on the list is the motherboard, which consumes no more than 50 watts.

Knowing all the parameters of their components, the user will be able to decide how to calculate the power supply for the computer.

What system can fit a 500 watt power supply?

It’s worth starting with the motherboard - an average board in terms of parameters may be suitable. It can have up to four sticks for RAM, one slot for a video card (or several - it depends only on the manufacturer), a socket for a processor no older than support for an internal hard drive (size does not matter - only revolutions), and a 4-pin connector for the cooler.

The processor can be either dual-core or four, the main thing is the lack of overclocking (it is indicated by the letter "K" at the end of the processor model number).

The cooler for such a system should be with four connectors, because only four pins will provide control of the fan speed. The lower the speed, the less energy is consumed and the less noise.

The video card, if it is NVIDIA, can be from GTS450 to GTS650, but not higher, since only these models can do without additional power and do not support overclocking.

The remaining components will not greatly affect the energy consumed. Now the user is more oriented in how to calculate the power supply for a PC.

The main manufacturers of power supplies for 500 watts

The leaders in this area are EVGA, Zalman and Corsair. These manufacturers have established themselves as high-quality suppliers of not only power supplies, but also other PC components. AeroCool also boasts popularity in the market. There are other manufacturers of power supplies, but they are less well-known and may not have the necessary parameters.

Description of power supplies

Opens the EVGA 500W power supply list. This company has long established itself as a quality manufacturer of PC components. So, this block has a bronze certificate 80 Plus - this is a special guarantee of quality, which means good stability of the block from voltage surges. 12 millimeters. All cables have a shield braid, and the plugs are labeled where and what they belong to. Guarantee of use - 3 years.

The next representative is AeroCool KCAS 500W. This manufacturer deals exclusively with cooling and powering the PC. This power supply can withstand input voltage up to 240 volts. Bronze 80 Plus certified. All cables have a screen braid.

The third manufacturer of a 500w computer power supply is ZALMAN Dual Forward Power Supply ZM-500-XL. This company has also established itself as a manufacturer of quality PC products. The fan diameter is 12 centimeters, only the main cables have a screen braid - the rest are fastened with ties.

The following is a lesser known manufacturer of a 500w computer power supply - ExeGate ATX-500NPX. Of the 500 watts shown, 130 watts are for 3.3 volt equipment and the remaining 370 watts are for 12 volt equipment. The fan, like the previous blocks, has a diameter of 120 millimeters. The cables do not have a screen braid, but are held together with cable ties.

Last on the list, but not the worst, is the Enermax MAXPRO, which has an 80 Plus Bronze Quality Certification. This power supply is designed for a motherboard, the size of which corresponds to the ATX marking. All cables are shielded.

Conclusion

This article described in detail how to calculate a power supply for a computer, what equipment is best suited for such purposes, a description of the blocks themselves from leading manufacturers and their photos.

When you assemble your computer, this has its own significant advantages, since all components in a personal computer (PC) play their role with the system unit - a processor and RAM for quick operations, a video card for displaying the graphic part, a motherboard for connecting everything this together. That is why it is important to select components not only according to how they will meet your needs, but also because of how they will interact with each other.
In particular, there are errors when the motherboard does not "accept" the processor, or there is no place in the case to install a video card.
But even if you seem to have picked up all the components and they fit together, then when choosing a power supply unit (PSU), questions often arise. The most common is how much power is needed to make all components "feel" comfortable.

In order to calculate the power of the power supply, you can go in several ways. For example, you can ask the consultants in the store and hope that the store employee will be sufficiently knowledgeable in this and will be able to advise and select the right one.

Or you can take and buy a power supply with a capacity of 600-1000 watts and just don’t think about it. either way, that's enough. Yes, you can do this and overpay for the extra 600 watts. in fact, 400 watts for example could be enough for you. It seems to me that this is not a way out of the situation. If only for the lazy and who do not mind the money.

You can also look on the Internet how much power is needed for each of the components of the future system unit, and then calculate the required power. In this case, it should be borne in mind that the total power of all components must be less than the maximum output power of the power source. It is also worth knowing and remembering that the characteristics indicate the maximum power consumption of the components. during operation, energy is consumed unevenly by everyone (turning on, turning off, recording information, launching many programs, a complex episode in the game, etc.).

For example, the power consumption of components looks something like this:

Even 3 years ago, it was believed that a 350W power supply was enough for the eyes to power any, the most fancy home computer. Take a more powerful PSU from a well-known manufacturer, and you can at least hang yourself with various devices - you don’t need to count anything. But the crazy race for megahertz and fps is making its own adjustments: a new video accelerator from nVidia has appeared on the market - the GeForce GTX 580, ATI is preparing a retaliatory strike, and the user is already recommended to stock up on a 600W PSU! The question naturally arises: power supply replacement upgrade is no longer possible?

It is not so difficult to answer this question - it is necessary calculate computer power. Be able to calculate system power consumption useful for computer assembly and upgrade any configuration. How to find out why the computer does not turn on, or will the noname block on 230W support an additional HDD? We will try to talk about this below.

The principle of operation of the power supply

Very often on iron forums you can find sad stories about how someone's power supply burned out and took his mother, percent, vidyukha, screw and Murzik's cat to the other world. Why are the BPs on fire? And why does the load burn with a blue flame aka filling of the system unit? To answer these questions, let's take a brief look at principle of operation of a switching power supply.

Computer power supplies use a double conversion method with feedback. The conversion takes place due to the transformation of current with a frequency not of 50 Hz, as in a household network, but with frequencies above 20 kHz, which allows the use of compact high-frequency transformers with the same output power. Therefore, a computer power supply is much smaller than classic transformer circuits, which consist of a rather impressive step-down transformer, a rectifier and a ripple filter. If a computer power supply were made according to this principle, then at the required output power it would be the size of a system unit and would weigh 3–4 times more (suffice it to recall a television transformer with a power of 200–300 W).

Switching PSU has a higher efficiency due to the fact that it works in the key mode, and the regulation and stabilization of the output voltages occurs by the method of pulse-width modulation. Without going into details, the principle of operation is that regulation occurs by changing the pulse width, that is, its duration.

Briefly the principle of operation pulse power supply is simple: to use high frequency transformers, we need to convert the current from the network (220 volts, 50 Hz) to high frequency current (about 60 kHz). The current from the electrical network goes to the input filter, which cuts off high-frequency impulse noise generated during operation. Further - to the rectifier, at the output of which there is an electrolytic capacitor to smooth out ripples. Next, a rectified DC voltage of the order of 300 volts is supplied to a voltage converter, which converts the input DC voltage into an AC voltage with a rectangular shape of high-frequency pulses.

The converter includes a pulse transformer, which provides galvanic isolation from the network and voltage reduction to the required values. These transformers are made very small compared to classical ones, they have a small number of turns, and a ferrite core is used instead of an iron core. Then the voltage removed from the transformer goes to the secondary rectifier and high-frequency filter, consisting of electrolytic capacitors and inductances. To ensure stable voltage and operation, modules are used that provide smooth switching on and overload protection.

So, as you may have noticed from the above, a very high voltage current flows in the computer power supply circuit - ~ 300 volts. Now let's imagine what happens if any key element of the circuit fails and the protection does not work. The high voltage current will briefly enter the load (until the PSU burns out), and some of the contents of the system unit will most likely not survive this.

Why is the BP on fire?

There are many reasons: the fan stopped, a screw fell inside, the insides clogged with dust, etc. But we are interested in another point.

The switching power supply takes as much energy from the network as the load consumes. Accordingly, if the power consumed by the load is higher than the power for which the PSU is designed, then the strength of the current flowing through the circuits of the unit will also be higher than that for which the conductors and elements are designed, which will lead to strong heating and, as a result, to the output of the power supply out of service. That is why there is an output power sensor at the output of the PSU, and the protective circuit will immediately turn off the power supply if the calculated load power is greater than the maximum power of the PSU.

So, if you thoughtlessly overload the power supply, then at best it simply will not turn on, and at worst it will burn out, so it is always useful to at least estimate the load power.

What is power

Power is a physical quantity that characterizes the energy given or received by an object per unit of time. Accordingly, power can be allocated (output) and absorbed (consumed).

Power, like energy, can be of various types (mechanical, electrical, thermal, acoustic, electromagnetic, wave, etc.), which, in turn, are related to the nature of this energy.

The ratio of the power released during the conversion of energy to the power consumed is called the coefficient of performance (COP), which characterizes the efficiency of this conversion.

As is known from the school physics course, the power P [W] for a DC circuit is directly proportional to the voltage U [V] and the current strength I [A] in the circuit section:

P=I*U

This formula can be used both to calculate the power consumed by the device, and to calculate the output power of the PSU, as well as for the dissipated thermal power.

Accordingly, the thermal power released on the element of the power supply circuit (heating of the element) will be directly proportional to the strength of the current passing through all consumers.

Probably, it is not necessary to explain that the total power of all components must be less than the maximum output power of the power supply.

It should also be noted that the system consumes power unevenly. Power peaks occur when turning on a PC or a separate device, using servos, increasing the computing load on the system, etc. Manufacturers often indicate peak power values ​​​​for devices with high power consumption. Thus, a rough estimate of the maximum power consumption of the load can be simply summed up the power of all devices connected to the PSU:

P = p(1) + p(2) + p(3) + … + p(i)

BP standards

But in order to calculate power and identify problems with it, you need to know some data about the power supply itself. Let's start with standards.

The first power supply standard for IBM PC compatibles was AT. It provided PSU power up to 200W, which was enough with a large margin, since CPUs consumed a meager amount of energy by today's standards, and only a few users could afford a second HDD.

With the release of the Pentium II, AT could no longer provide the output power required for an average PC (230-250W) and gave way to ATX. ATX differs from AT in the presence of an additional power supply + 3.3V, the presence of power in the + 5V circuit in Standby mode and the possibility of software shutdown. There are no fundamental differences in circuitry.

Pentuim IV has made further adjustments. This processor consumes so much power that a standard ATX block can no longer provide stable power in the 12V circuit. The cross section of the conductor and the area of ​​reliable contact with the connectors are insufficient, which can lead to damage to the motherboard, so an additional 4-pin connector has appeared.

Considering the "gluttony" of modern CPUs and video adapters, it seems that another change in the standard is waiting for us soon.

We read the characteristics of the power supply

That big beautiful figure that is indicated in the power supply model shows the total power of the device. We should be interested in such indicators as effective load (efficiency) and time between failures at a certain load and temperature. The first indicator indicates how much power the load will consume, and how much will be released in the form of heat, that is, with a declared power of 350W and an effective load of 68%, we will get 240W. For different manufacturers, this figure ranges from 65% to 85%. The second indicator gives us data on the recommended operating conditions of the PSU, for example, 100,000 hours at a load of 75% and a temperature of 25 degrees Celsius. Other indicators relate to the values ​​​​of deviations in input and output voltage, protection against overloads, short circuits and overheating, etc.

However, there is another block of characteristics. The fact is that the total power of the unit is the sum of the power indicators for individual circuits. They are indicated on the cover of the power supply in a special plate. Using the formula above, you can calculate the minimum maximum load power for each circuit. Adding the resulting power, we get the effective power of the PSU.

The power for each output is also important to consider, since the load consumes current of different voltages and will load the corresponding power supply circuit.

CPU

Processor, one of the most voracious element in a computer. No wonder they gave him a separate outlet! The power consumed by a particular CPU model is usually known and specified by the manufacturer. It can also be calculated by multiplying the current consumed by the processor (usually also indicated) by the voltage. You can see the power of the most common CPUs in the table.

Difficulties with calculating the power consumed by the processor arise if the CPU is overclocked. Power increases with increasing clock frequency and core voltage. If the increase in voltage is easy to take into account, then the coefficient of dependence of the consumed current on the frequency can only be found empirically. It can be said very approximately that with an increase in frequency by 100 MHz, the power consumption increases by 0.6–1.0W.

Video adapter

Modern video accelerators in terms of "gluttony" give odds to the processor. The video chip contains an impressive number of transistors, the frequencies are also high, and the onboard memory needs power.

The power consumed by a video card is very dependent on its state: whether it is in standby mode, used in 2D applications, or renders a complex 3D scene. It is not possible to give exact values ​​for the change in power consumption, but tests show that when the system is loaded with a 3D application in high screen resolution, the power consumption of the system can increase by 80-200W compared to the unloaded state.

Drives

A feature of the drives is the presence of mechanical parts in the design, in particular electric motors that consume current with a voltage of 12 volts. It is at the moment of positioning the HDD heads or opening the CD-drive tray that the increase in energy consumption occurs. We have witnessed a PSU shutdown due to an attempt to open a CD-ROM.

We should also mention CD-RW and DVD drives. Due to the increased power of the laser beam, these drives consume somewhat more energy, but in comparison, the figure is insignificant - ~ 15W.

USB and IEEE 1394

When devices are "hot-plugged" there is also a surge in power consumption, and each device consumes additional power. Thus, the power supply of temporarily connected devices must be taken into account when planning the power reserve of the power supply.

Other factors

When buying a power supply, you always need to leave a certain amount of power. This is due to the possibility of future upgrades and the installation of additional equipment. You should also take into account seasonal changes in working conditions, wear and tear of the PSU. For example, dust greatly affects the operation of the unit. Dust is not only a thermal insulator that prevents cooling, and not only a hindrance to the operation of fans. It is also an excellent conductor of static electricity. So dust is primarily dangerous for the computer, and with an increase in power consumption (that is, an increase in voltage when turning on a device), a component may fail. The situation is similar with wear - it brings the failure of the system closer.

What to look for when buying a PSU

First of all, on the quality of performance. It can even be measured by weight. The lightness of a 600-watt unnamed PSU is sometimes surprising compared to the heaviness of a 350-watt Chiftec. A solid weight means that the manufacturer does not save on good massive radiators and transformers with a power reserve, and even on the power elements of the PSU case.

Also, powerful power supplies are equipped with a large number (from 7 and more) of high-quality connectors for connecting various internal devices.

If possible, it is advisable to check the stability of the output voltage in operation. To do this, there are various utilities that allow you to observe and record power characteristics in real time. Usually they come with software to the motherboard.

And finally, you should not buy blocks without a name or with an unfamiliar name of the manufacturer.

conclusions

So, it is simply necessary to calculate the power consumption of the load and the actual output power of the power supply when making decisions about buying a new device or upgrading. And although modern blocks have reliable protection circuits, it will be very unpleasant if, when trying to read information from a flash drive, a brand new power supply immediately turns off.

Authors: Kirill Bohinek, Pavel Sukhochev

To convert the alternating voltage coming from the network into a constant one, power the computer components and ensure that they maintain power at the required level - these are the tasks of the power supply. When assembling a computer and updating components in it, you should carefully look at the power supply that will serve the video card, processor, motherboard and other elements. You can choose the right power supply for your computer after you read the material in our article.

To determine the power supply that is needed for a particular computer assembly, you need to operate with data on the energy consumption of each individual component of the system. Of course, some users decide to buy a power supply with maximum power, and this is really an effective way not to make a mistake, but very costly. The price of a power supply unit of 800-1000 watts may differ from the model of 400-500 watts by 2-3 times, and sometimes it is quite enough for selected computer components.

Some buyers, when collecting computer components in a store, decide to ask a sales assistant for advice on choosing a power supply. This way to decide on a purchase is far from the best, given the not always sufficient qualifications of sellers.

The ideal option is to independently calculate the power of the power supply. This can be done using special sites and is quite simple, but this will be discussed below. For now, we suggest that you familiarize yourself with some general information about the power consumption of each component of the computer:

The main components of the computer are listed above, according to which the power of the power supply sufficient for a particular computer assembly is calculated. Please note that an additional 50-100 watts must be added to the figure obtained by such a calculation, which will be spent on the operation of coolers, keyboards, mice, various accessories and a “reserve” for the system to work correctly under load.

Services for calculating the power supply of a computer

It is not always easy to find information on the required power for a particular computer component on the Internet. In this regard, the process of independently calculating the power of the power supply can take a lot of time. But there are special online services that allow you to calculate the power consumed by components and offer the best option for a power supply for a computer.

One of the best online calculators for calculating the power supply. Among its main advantages are a user-friendly interface and a huge base of components. In addition, this service allows you to calculate not only the “basic” power consumption of computer components, but also the increased power consumption, which is typical when “overclocking” a processor or video card.

The service can calculate the required power of the computer's power supply using simplified or expert settings. The advanced option allows you to set the parameters of components and select the mode of operation of the future computer. Unfortunately, the site is completely in English, and it will not be convenient for everyone to use it.

The well-known company MSI, which produces gaming components for computers, has a calculator on its website for calculating the power supply. It is good in that when you select each component of the system, you can see how much the required power of the power supply changes. Also, a clear advantage can be considered the full localization of the calculator. However, when using the service from MSI, you should remember that you will have to buy a power supply with a power of 50-100 watts higher than he recommends, since this service does not take into account the keyboard, mouse and some other additional accessories when calculating the consumption.