The power supply is designed to supply electric shock all computer components. It must be powerful enough and have a small margin for the computer to work stably. In addition, the power supply must be of high quality, since the service life of all computer components greatly depends on it. By saving $10-20 on the purchase of a high-quality power supply, you risk losing system unit costing $200-1000.
The power of the power supply is selected based on the power of the computer, which mainly depends on the power consumption of the processor and video card. It is also necessary that the power supply has at least 80 Plus Standard certification. The optimal price/quality ratio are Chieftec, Zalman and Thermaltake power supplies.
For an office computer (documents, Internet), a 400 W power supply is sufficient; take the most inexpensive Chieftec or Zalman, you won’t go wrong.
Power supply Zalman LE II-ZM400
For a multimedia computer (movies, simple games) and gaming computer in the entry class (Core i3 or Ryzen 3 + GTX 1050 Ti), the most inexpensive 500-550 W power supply from the same Chieftec or Zalman will do; it will have a reserve in case of installing a more powerful video card.
Chieftec GPE-500S power supply
For a mid-class gaming PC (Core i5 or Ryzen 5 + GTX 1060/1070 or RTX 2060), a 600-650 W power supply from Chieftec is suitable, if there is an 80 Plus Bronze certificate, then good.
Chieftec GPE-600S power supply
For powerful gaming or professional computer(Core i7 or Ryzen 7 + GTX 1080 or RTX 2070/2080) it is better to take a 650-700 W power supply from Chieftec or Thermaltake with an 80 Plus Bronze or Gold certificate.
Chieftec CPS-650S power supply
2. Power supply or case with power supply?
If you are assembling a professional or powerful gaming computer, then it is recommended to select a power supply separately. If we are talking about office or ordinary home computer, then you can save money and purchase a good case complete with a power supply, which will be discussed.
3. What is the difference between a good power supply and a bad one?
The cheapest power supplies ($20-30) by definition cannot be good, since in this case manufacturers save on everything possible. Such power supplies have bad heatsinks and a lot of unsoldered elements and jumpers on the board.
At these places there should be capacitors and chokes designed to smooth out voltage ripples. It is because of these ripples that the motherboard, video card, hard drive and other computer components fail prematurely. In addition, such power supplies often have small radiators, which cause overheating and failure of the power supply itself.
A high-quality power supply has a minimum of unsoldered elements and larger radiators, which can be seen from the installation density.
4. Power supply manufacturers
Some of the best power supplies are made by SeaSonic, but they are also the most expensive.
Well-known enthusiast brands Corsair and Zalman recently expanded their range of power supplies. But their most budget models have rather weak filling.
AeroCool power supplies are among the best in terms of price/quality ratio. The well-established cooler manufacturer DeepCool is closely joining them. If you don't want to overpay for an expensive brand, but still get a high-quality power supply, pay attention to these brands.
FSP produces power supplies under different brands. But I would not recommend cheap power supplies under their own brand; they often have short wires and few connectors. Top-end FSP power supplies are not bad, but they are no longer cheaper than famous brands.
Of those brands that are known in narrower circles, we can note the very high-quality and expensive be quiet!, the powerful and reliable Enermax, Fractal Design, the slightly cheaper but high-quality Cougar and the good but inexpensive HIPER as a budget option.
5. Power supply
Power is the main characteristic of a power supply. The power of the power supply is calculated as the sum of the power of all computer components + 30% (for peak loads).
For an office computer, a minimum power supply of 400 watts is sufficient. For a multimedia computer (movies, simple games), it is better to take a 500-550 Watt power supply, in case you later want to install a video card. For a gaming computer with one video card, it is advisable to install a power supply with a power of 600-650 Watts. A powerful gaming PC with multiple graphics cards may require a power supply of 750 watts or more.
5.1. Power supply power calculation
- Processor 25-220 Watt (check on the seller’s or manufacturer’s website)
- Video card 50-300 Watt (check on the seller’s or manufacturer’s website)
- Entry class motherboard 50 Watt, mid class 75 Watt, high class 100 Watt
- Hard drive 12 Watt
- SSD 5 Watt
- DVD drive 35 Watt
- Memory module 3 Watt
- Fan 6 Watt
Don’t forget to add 30% to the sum of the powers of all components, this will protect you from unpleasant situations.
5.2. Program for calculating power supply power
To more conveniently calculate the power of a power supply, there is an excellent program “Power Supply Calculator”. It also allows you to calculate the required source power uninterruptible power supply(UPS or UPS).
The program works for everyone Windows versions with "Microsoft . NET Framework» version 3.5 or higher, which is usually already installed by most users. You can download the “Power Supply Calculator” program and if you need the “Microsoft .NET Framework” at the end of the article in the “” section.
6.ATX standard
Modern power supplies have the ATX12V standard. This standard can have several versions. Modern power supplies are manufactured according to ATX12V 2.3, 2.31, 2.4 standards, which are recommended for purchase.
7. Power correction
Modern power supplies have a power correction function (PFC), which allows them to consume less energy and heat less. There are passive (PPFC) and active (APFC) power correction circuits. The efficiency of power supplies with passive power correction reaches 70-75%, with active power correction - 80-95%. I recommend purchasing power supplies with active power correction (APFC).
8. Certificate 80 PLUS
A high-quality power supply must have an 80 PLUS certificate. These certificates come in different levels.
- Certified, Standard – entry-level power supplies
- Bronze, Silver – mid-class power supplies
- Gold – high-end power supplies
- Platinum, Titanium – top power supplies
The higher the certificate level, the higher the quality of voltage stabilization and other parameters of the power supply. For a mid-range office, multimedia or gaming computer, a regular certificate is sufficient. For a powerful gaming or professional computer, it is advisable to take a power supply with a bronze or silver certificate. For a computer with several powerful video cards - gold or platinum.
9. Fan size
Some power supplies still come with an 80mm fan.
A modern power supply should have a 120 or 140 mm fan.
10. Power supply connectors
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ATX (24-pin) - motherboard power connector. All power supplies have 1 such connector. |
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CPU (4-pin) - processor power connector. All power supplies have 1 or 2 of these connectors. Some motherboards have 2 processor power connectors, but can also operate from one. |
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SATA (15-pin) - power connector for hard drives and optical drives. It is advisable that the power supply have several separate cables with such connectors, since connecting a hard drive and an optical drive with one cable will be problematic. Since one cable can have 2-3 connectors, the power supply must have 4-6 such connectors. |
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PCI-E (6+2-pin) - video card power connector. Powerful video cards require 2 of these connectors. To install two video cards, you need 4 of these connectors. |
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Molex (4-pin) - power connector for older hard drives, optical drives and some other devices. In principle, it is not required if you do not have such devices, but it is still present in many power supplies. Sometimes this connector can supply voltage to the case backlight, fans, and expansion cards. |
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Floppy (4-pin) - drive power connector. Very outdated, but can still be found in power supplies. Sometimes some controllers (adapters) are powered by it. |
Check the configuration of power supply connectors on the seller's or manufacturer's website.
11. Modular power supplies
In modular power supplies, excess cables can be unfastened and they will not get in the way in the case. This is convenient, but such power supplies are somewhat more expensive.
12. Setting up filters in the online store
- Go to the “Power Supplies” section on the seller’s website.
- Select recommended manufacturers.
- Select the required power.
- Set other parameters that are important to you: standards, certificates, connectors.
- Look through the items sequentially, starting with the cheapest ones.
- If necessary, check the connector configuration and other missing parameters on the manufacturer’s website or another online store.
- Buy the first model that meets all parameters.
Thus, you will receive the best price/quality ratio power supply that meets your requirements at the lowest possible cost.
13. Links
Corsair CX650M 650W power supply
Thermaltake Smart Pro RGB Bronze 650W power supply
Power supply Zalman ZM600-GVM 600W
Characteristics of power supplies
There are several parameters that determine the input and output power, as well as the performance characteristics of the power supply. These settings are common to most power supplies.
Loading the power supply
Regardless of these characteristics, if you want to test correctly and accurately power unit, make sure that there is a load on at least one power supply line, and even better, that there is a load on all three lines. This is one of the reasons why we recommend testing the power supply while it is installed in the computer, rather than removed. You can use a spare one as a makeshift test bench motherboard and one or more hard drives to provide load on the power lines.
Power supply power
The system integrator must provide technical specifications for all components that are used in the system. This information is usually reflected in reference guide, but the specifications power supply, as a rule, can be recognized by the sticker on it. PSU manufacturers also usually provide this information, so it is preferable if you can identify the manufacturer and check the data directly or online.
The input specifications refer to the AC mains voltage, while the output specifications refer to the current in amperes along each line. By multiplying the current by the voltage, you can calculate the power power supply for each line:
Watts (W) = Volts (V) x Amps (A)
For example, if one of the +12 V lines is specified at 8 A, the power is 96 W, according to this formula. By adding the voltage/current at each of the main outputs, you can calculate the total power power supply. Note that only positive voltages are involved in these calculations. Negative voltages, Standby, Power_Good lines and other auxiliary signals are not taken into account when calculating the power of the power supply.
The following table shows calculations for several power supplies of different power, meeting the ATX12V/EPS12V standards, manufactured by Corsair (www.corsair.com).
| Typical characteristics of ATX12V/EPS12V power supply, output values | |||||||
| Model | VX450W | VX550W | HX650W | HX750W | HX850W | TX950W | AX1200 |
| +12 V (A) | 33 | 41 | 52 | 62 | 70 | 78 | 100 |
| -12V(A) | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 |
| +5 VSB (A) | 2.5 | 3 | 3 | 3 | 3 | 3 | 2.5 |
| +5 V (A) | 20 | 28 | 30 | 25 | 25 | 25 | 30 |
| +3.3 V (A) | 20 | 30 | 24 | 25 | 25 | 25 | 30 |
| Max +5 V/+3.3 V (W) | 130 | 140 | 170 | 150 | 150 | 150 | 180 |
| Claimed power (W) | 450 | 550 | 650 | 750 | 850 | 950 | 1200 |
| Rated power (W) | 548 | 657 | 819 | 919 | 1015 | 1111 | 1407 |
In fact, all power supplies reach their maximum values on the +3.3 V and +5 V lines. The calculated maximum power implies a total maximum consumption across all lines and is not achieved in real conditions. Therefore, the power supply power declared by the manufacturer is usually less than the calculated one.
While store-bought PCs often come with low-power power supplies of 350W or less, high-wattage PSUs are often recommended for full-fledged desktop systems. Unfortunately, even relatively high power ratings stated for cheap power supplies cannot always be trusted. For example, we saw power unit with a declared power of 650 W, the actual power of which was an honest 200 W. Another problem is that there are only a few companies making power supplies for PCs. Most power supplies that you can find on store shelves are made by one of several manufacturers, but can be sold under different brands, names, models, etc. Since not every buyer has equipment with which to test the real power at the outputs, you should trust only well-known, trusted brands that offer high-quality power supplies.
Most power supplies are considered universal, meaning they can be used anywhere in the world. In other words, they can operate in AC networks of 127 V/50 Hz (USA), 240 V/50 Hz (Europe and some other countries), 220 V/50 Hz (Russia). Switching to the appropriate input current mode is usually carried out automatically, although power supplies equipped with a 127/240 V toggle switch on the rear panel are still sometimes found.
In an AC network, the voltage can fluctuate, which is taken into account when developing the design of a power supply that has special stabilization circuits at the input in front of the pulse voltage converter. As a rule, the effect of voltage “sag” is taken into account, that is, its decrease on the way to the outlet in the apartment. For this reason power unit, designed for the European standard 240 V, can operate in Russian 220 V networks.
Attention! If your power supply does not switch automatically, make sure the input voltage switch is set correctly. If you plug the power supply into a 120 V outlet with the toggle switch set to 240 V, no unpleasant consequences will occur, but the power supply will not work until you change the toggle switch. On the other hand, if the toggle switch is fixed at 120 V, and the power supply is connected to a 220/240 V outlet, it may fail.
Other characteristics and certificates
In addition to power, there are other characteristics and functions that power supply manufacturers provide their products with.
We have dealt with a huge number of different computers and our experience is that if there are several computers in the room and there is a sudden drop in voltage in the network, then a better and more powerful power unit will keep the computer in working condition, while PCs with weak power supplies are turned off.
Better quality power unit also helps protect your system. In particular, using power supplies from manufacturers such as PC Power and Cooling, you do not have to worry about the safety of PC components in the following cases:
- 100% power outage for any duration.
- Short-term voltage drop.
- Peak increase in voltage up to 2500 V at the input (for example, as a result of a lightning strike or a short-term power surge).
High-quality power supplies have an extremely low current supplied to ground (less than 500 mA). This is important from a PC safety point of view if it is not connected to ground.
As you can see, the additional characteristics of power supplies are quite strict and such capabilities can only be found when we are talking about fairly expensive products.
You may also come across many other criteria for evaluating BP. The power supply is the PC component that many buyers pay attention to last, so many system integrators also do not pay due attention to the choice of power supply. In the end, it is more profitable for a PC seller to install a more powerful processor or HDD larger volume than equipping it with a higher quality power supply.
It is for this reason that when choosing a computer or upgrading an existing one, you need to be very careful about the quality power supply, which you plan to use. In the same time, various characteristics and the values given in the power supply specifications can confuse many buyers. Therefore, here we provide a list of the most common power supply parameters:
- Mean Time Between Failures (MTBF) or Mean Time To Failure (MTTF). The estimated time interval, expressed in hours, during which the power supply is expected to operate before failure. Power supplies typically have MTBF ratings (e.g. 100,000 hours or more), which obviously are not the result of actual empirical testing. In fact, manufacturers use published standards to calculate MTBF based on the failure ratings of individual power supply components. MTBF numbers for power supplies often include the load level that is expected (as a % of total power) as well as the ambient temperature at which the values are relevant.
- Input (or operating) range. Indicates the voltage range with which the power supply can operate. For example, for a US 120V AC mains input range is typically 90-135V, while for European 240V AC mains the typical range is 180-270V.
- Peak current when turned on. The maximum current value at the moment immediately after turning on the power supply, expressed in amperes at a given voltage. The lower this value, the less temperature shock the system experiences.
- Shutdown time. The amount of time (in milliseconds) that the PSU can maintain voltage levels within specifications in the event of a sudden loss of incoming current. This allows the computer to continue operating after a momentary power loss without rebooting or shutting down. Values of 15-30 ms are standard for modern power supplies, but the larger this value, the better. According to the Power Supply Design Guide for Desktop Platform Form Factors specification, the minimum shutdown time is 16 ms. The shutdown time also greatly depends on the current load on the power supply. The shutdown time generally reflects the minimum time measured under maximum load. If the load decreases, the shutdown time increases proportionally. For example, if a 1000 W power supply has a latency of 20 ms according to its specification (measured under a 1000 W load), then at a load of 500 W (half the specified power) the boot time will double, and at a load of 250 W it will quadruple. In fact, this is one of the reasons to purchase a more powerful power supply than is required given the requirements of the system components.
- Transition time. The amount of time (in milliseconds) it takes the power supply to restore its output voltages (to specification) after changing to another operating mode. In other words, we are talking about the time during which the voltages at the outputs of the power supply are stabilized when one of the PC components is turned on or off. The power supply checks the output load at regular intervals. When the device is turned off (for example, the optical drive stops spinning the disk), the power supply may continue to supply a high level of current to the power connector for a short period of time. This excess voltage is called "surge" and the transition time refers to the amount of time it takes for the outputs to return to their standard voltage specifications. Changing the operating mode of any of the PC components is considered a voltage surge and can cause crashes and freezes of the computer, as it affects the voltage supplied to other outputs. While one of the main problems with switching power supplies when they first came out, "overshoot" has been noticeably reduced in recent years. Transition times are often expressed as time intervals, but sometimes they are expressed in terms of the maximum amount of change in output voltages (for example, the specification states that “the output voltage level can vary by up to 20% when the load conditions change).
- Overvoltage protection. This parameter defines the indicators for each output at which the power supply turns off one or another output. Can be expressed as either a %% of the specification value (e.g. 120% for +3.3 V and +5 V) or actual voltage values (e.g. +4.6 V for +3.3 V and +7 output V for +5 V output).
- Maximum load current. The maximum current (in amperes) that can safely pass through a particular output. The values are expressed in individual current for each voltage. Based on this data, you can not only calculate the total power of the power supply, but also check how many devices can be “hung” on a particular output.
- Minimum load current. Determines the smallest amount of current (in amperes) that must be supplied to a particular output for it to operate. If the current consumed at the output drops below the minimum, the power supply may fail or automatically turn off.
- Load stabilization (or load voltage stabilization). When the current on one or another output increases or decreases, the voltage values also change slightly - usually decreasing if the current increases. Load stabilization means changing the output voltage when there is a transition from minimum to maximum load (or vice versa). Values are expressed in +/- %%, typically ranging from +/-1% to +/-5% for +3.3V, +5V and +12V outputs.
- Mains voltage stabilization. The change in output voltage as the incoming AC current fluctuates from the lowest to the highest value (or vice versa). The power supply must use any AC current within its operating range while maintaining a stable output voltage (fluctuations of 1% or less are acceptable).
- Efficiency. The ratio of power supply output power to power consumption. Values of 65-85% are considered standard today. The remaining 15-35% is converted into thermal energy during the process of converting current from alternating to direct current. Although higher efficiency means the power supply will run cooler (which is a good thing) and lower energy bills. For the sake of higher efficiency of the power supply, accuracy, stability and reliability should not be sacrificed, as well as strict stabilization of the mains voltage and other characteristics.
- Noise, fluctuations, periodic and random deviations of the AC network. average value voltage fluctuations at the power supply outputs depending on all the effects of the alternating current network associated with voltage drops, usually varying in millivolts or percentage of the rated value. The lower this indicator, the better. For quality power supplies, voltage drops are typically 1% of the rated output voltage (or less). Therefore, for a +5V output they can be as high as 0.05V or 50mV (millivolts). Voltage drops can be caused by internal design features of the power supply, voltage fluctuations in the AC network, or random interference.
The power supply provides electricity to all PC components. We will tell you how this device works.
Even though your computer plugs into a standard electrical outlet, its components cannot draw power directly from the electrical outlet for two reasons.
Firstly, the network uses alternating current, and computer components require constant. Therefore, one of the tasks of the power supply is to “rectify” the current.
Secondly, different computer components require different supply voltages to operate, and some require several lines with different voltages at once. The power supply provides each device with current with the necessary parameters. For this purpose, it has several power lines. For example, the power connectors for hard drives and optical drives supply 5 V for electronics and 12 V for the motor.
Power supply characteristics
The power supply is the only source of electricity for all PC components, so the stability of the entire system directly depends on the characteristics of the current it produces. The main characteristic of a power supply is power. It should be at least equal to the total power that the PC components consume at maximum computing load, and even better if it exceeds this figure by 100 W or more. Otherwise, the computer will turn off at times of peak load or, what is much worse, the power supply will burn out, taking other system components with it to the next world.
For most office computers, 300 W is sufficient. The power supply of a gaming machine must have a power of at least 400 W - high-performance processors and fast video cards, as well as the additional cooling systems they require, consume a lot of energy. If the computer has several video cards, then 500- and 650-watt power supplies will be required to power it. There are already models on sale with a power of more than 1000 W, but buying them is almost pointless.
Often, power supply manufacturers shamelessly inflate the rated power value; this is most often encountered by buyers of cheap models. We advise you to choose a power supply based on testing data. In addition, the power of a power supply is most easily determined by its weight: the larger it is, the higher the likelihood that the actual power of the power supply matches the declared one.
In addition to the total power of the power supply, its other characteristics are also important:
Maximum current on individual lines. The total power of the power supply consists of the powers that it can provide on individual power lines. If the load on one of them exceeds the permissible limit, the system will lose stability even if the total power consumption is far from the power supply rating. The load on lines in modern systems is usually uneven. The 12-volt channel has the hardest time, especially in configurations with powerful video cards.
Dimensions. When specifying the dimensions of a power supply, manufacturers, as a rule, limit themselves to the designation of the form factor (modern ATX, outdated AT or exotic BTX). But manufacturers of computer cases and power supplies do not always strictly adhere to the norm. Therefore, when purchasing a new power supply, we recommend comparing its dimensions with the dimensions of the “seat” in your PC case.
Connectors and cable lengths. The power supply must have at least six Molex connectors. A computer with two hard drives and a pair of optical drives (for example, a DVD-RW writer and a DVD reader) already uses four such connectors, and other devices can also be connected to Molex - for example, case fans and video cards with an AGP interface.
The power cables must be long enough to reach all required connectors. Some manufacturers offer power supplies whose cables are not soldered into the board, but are connected to connectors on the case. This reduces the number of wires dangling in the case, and therefore reduces the clutter in the system unit and promotes better ventilation of its interior, since it does not interfere with the air flow circulating inside the computer.
Noise. During operation, the components of the power supply become very hot and require increased cooling. For this purpose, fans built into the PSU case and radiators are used. Most power supplies use one 80 or 120 mm fan, and the fans are quite noisy. Moreover, the higher the power of the power supply, the more intense the air flow is required in order to cool it. To reduce noise levels, high-quality power supplies use circuits to control fan speed in accordance with the temperature inside the power supply.
Some power supplies allow the user to determine the fan speed using a regulator on the back of the power supply.
There are power supply models that continue to ventilate the system unit for some time after the computer is turned off. This allows PC components to cool down faster after use.
Presence of a toggle switch. The switch on the back of the power supply allows you to completely de-energize the system if you need to open the computer case, so its presence is welcome.
Additional power supply characteristics
High power supply power alone does not guarantee high-quality performance. In addition to it, other electrical parameters are also important.
Efficiency factor (efficiency). This indicator indicates what share of the energy consumed by the power supply from the electrical network goes to the computer components. The lower the efficiency, the more energy is wasted on wasteful heat. For example, if the efficiency is 60%, then 40% of the energy from the outlet is lost. This increases power consumption and leads to strong heating of the power supply components, and therefore to the need for increased cooling using a noisy fan.
Good power supplies have an efficiency of 80% or higher. They can be recognized by the “80 Plus” sign. Recently, three new, more stringent standards have been in effect: 80 Plus Bronze (efficiency of at least 82%), 80 Plus Silver (from 85%) and 80 Plus Gold (from 88%).
The PFC (Power Factor Correction) module allows you to significantly increase the efficiency of the power supply. It comes in two types: passive and active. The latter is much more efficient and allows you to achieve an efficiency level of up to 98%; a power supply with passive PFC is characterized by an efficiency of 75%.
Voltage stability. The voltage on the lines of the power supply fluctuates depending on the load, but it should not go beyond certain limits. Otherwise, system malfunctions or even failure of individual components may occur. The first thing you can rely on for voltage stability is the power of the power supply.
Safety. High-quality power supplies are equipped with various systems to protect against power surges, overloads, overheating and short circuits. These features protect not only the power supply, but also other components of the computer. Note that the presence of such systems in the power supply does not eliminate the need to use uninterruptible power supplies and network filters.
Main characteristics of the power supply
Each power supply has a sticker indicating its technical characteristics. The main parameter is the so-called Combined Power or Combined Wattage. This is the maximum total power for all existing power lines. In addition, the maximum power for individual lines also matters. If there is not enough power on a certain line to “feed” the devices connected to it, then these components may operate unstably, even if the total power of the power supply 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: to do this, you need to multiply the current by the voltage in the corresponding line.
12 V. 12 volts are supplied primarily to powerful consumers of electricity - the video card and the central processor. The power supply must provide as much power as possible on this line. For example, a 12-volt power supply line is designed for a current of 20 A. At a voltage of 12 V, this corresponds to a power of 240 W. High-end graphics cards can deliver up to 200W or more. They are powered via two 12-volt lines.
5 V. The 5V lines supply power to the motherboard, hard disks And optical drives PC.
3.3 V. The 3.3V lines go only to the motherboard and provide power to the RAM.
An important criterion will be the efficiency of the power supply. Efficiency factor (efficiency) is the ratio of the useful power supplied by the power supply to that consumed by it from the network. If the PC power supply circuit contained only a transformer, its efficiency would be about 100%.
Let's consider an example when a power supply (with a known efficiency of 80%) provides an output power of 400W. If this number (400) is divided by 80%, we get 500W. A power supply with the same characteristics, but with lower efficiency (70%), will already consume 570W.
But – you don’t need to 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. 80 Plus certification, however, is carried out only for 115 Volt networks (common in the USA), starting with the 80 Plus Bronze “class”, all units are tested for use in a 220V electrical network. For example, if certified in the 80 Plus Bronze class, the power supply efficiency is 85% at “half” power load, and 81% at the declared power.
The presence of a logo on the power supply indicates that the product meets the certification level.
The advantages of high efficiency: less energy is dissipated “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 supplies 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).
The load does not consume reactive power - it is 100% supplied back to the network in the next half-cycle. However, with increasing reactive power, the maximum (per period) current value increases.
Too much current in 220V wires - is this good? Probably not. Therefore, reactive power is combated whenever possible (this is especially true for really powerful devices that “cross” the limit of 300-400 Watts).
PFC – can be passive or active.
Advantages of the active method:
A power factor close to the ideal value is provided, up to a value close to 1. With PF=1, the current in the 220V wire will not exceed the value “power divided by 220” (in the case of lower PF values, the current is always somewhat more).
Disadvantages of active PFC:
As 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 autovoltage in conjunction with UPS sources.
Advantages of passive PFC:
There are no disadvantages of the active method.
Flaws:
The system is ineffective at high power values.
What exactly to choose? In any case, when purchasing a power supply unit of lower power (up to 400-450W), you will most often find 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 system unit provides for installing a power supply at the top of the case - then choose any model with a horizontally located fan. Larger diameter - less noise (with the same cooling power).
The rotation speed should vary depending on the internal temperature. When the power supply does not overheat, why do you need to turn the “valve” at all speeds and annoy the user with noise? There are power supply 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 - complete absence fan, this also happens). On the other hand, cooling is necessary to prevent parts from overheating (high power, in any case, leads to heat generation). At high power, you can’t do without a fan.
Note: the photo shows the result of modding (removing the standard slot grille, installing a Noktua fan and a 120 mm grill).
The power supply is the “heart” of power supply to computer components. It converts the incoming AC voltage into DC voltage of +3.3 V, +5 V, +12 V.
1. Computer power supply, its connectors and voltages
2. Power calculation
3. Main characteristics of power supplies
Computer power supply, its connectors and voltages
Computer components use the following voltages:
3.3V - Motherboard, memory modules, PCI, AGP, PCI-E cards, controllers
5B - Disk drives, drives, PCI, AGP, ISA
12V - Drives, AGP cards, PCI-E
As you can see, the same components can use different voltages.
Function PS_ON allows you to turn the power supply off and on programmatically. This function turns off the power supply when operating system will complete its work.
Signal Power_Good. When you turn on the computer, the power supply performs a self-test. And if the output supply voltage is normal, it sends a signal to the motherboard to the processor power management chip. If it does not receive such a signal, the system will not start.
It happens that the power supply does not have enough necessary connectors. You can get out of this situation by using various adapters and splitters:
Power calculation
The output powers for each line are usually written on the power supply sticker and are calculated using the formula:
Watts (W) = Volts (V) x Amps (A)
Thus, adding up all the powers for each line we get the total power of the power supply.
However, often the output power does not correspond to the declared one. It is better to take a slightly more powerful unit to compensate for the possible lack of power.
I think it’s better to give preference to proven brands, but it’s not a guarantee that the block will be of high quality. There is only one way to check it - open it. There must be massive radiators, high-capacity input capacitors, a high-quality transformer, all parts must be soldered
Main characteristics of power supplies
Power supplies cannot operate without load. When checking it, you need to connect something to it. Otherwise, it may burn out or, if there is protection, it will turn off.
You can start it by short-circuiting two wires on the main ATX connector, green and any black.
Characteristics: