PC Power Supplies

The power supply is used to process the input voltage from the power grid, transform it and divide it into power supply branches. The output of the power supply is several voltage levels distributed through different connectors. Do you know what parameters to look for when choosing a PC power supply? We will advise you.


Power Supply – Types

The computer power supply can be divided into five main categories.

Common ATX and Even Smaller SFX Power Supply

ATX power supply is the most common type. It is aimed for basic use, nothing special – if you do not aim to use your computer for gaming, crypto mining or PC tuning, this PSU type will do for you. If you're looking to power your compact office machine, you'll be probably more interested in SFX PC power supply  – a space-saving little brother of ATX.

Gaming Power Supply

gaming power supply offers great power, usually in the range of 400 up to 2 000 W. In most cases, you can expect this PSU to be ATX format, thanks to which they will fit into a wide range of PC cases and provide enough power for all gaming components. Gaming power supplies usually contain more connectors to power up multiple graphics cards or SSDs or HDDs.

PSU for Crypto Mining

Power supply for crypto mining provides similar or higher power than gaming PSU. The crucial difference is a higher number of PCI-E connectors to power more graphics cards simultaneously.

See more components for crypto mining in a specialised section on Crypto Mining.

PSU for Tuning

The PC tuning PSU is in demand mostly for aesthetic reasons. Usually, these are quiet PC power supplies that are suitable for PC cases with RGB lighting. The PC tuning power supply usually comes with suitable cable management equipment. 

Modular PSU

Modular PSU are usually different to other power supplies in that they come with detachable cables, thanks to which you gain a full control over your PC case. Modular cables can help air circulation and with that, they reduce dusting and high temperatures.


Passively cooled PC power supplies do not have a fan. They are cooled just by air circulation. They are ideal for less powerful office computers that do not produce much heat.

How to Choose the Right Power Supply

The best way to go about choosing an appropriate power supply is to follow a few simple rules given below.

Power Supply Must Have the Appropriate Power

The power of PCs is usually measured in Watts. Each component of your machine takes up a certain amount of these Watts. The table below shows an approximation of the required power. For a more accurate calculation of total power required, go to the computer power supply power requirements calculator at outervision.com.

Type Use
PSU up to 350W Office computers
PSU 400-450W Gaming PC and lower-power machines
PSU 500-550W Gaming PC and mid-range workstations
PSU 600-650W Gaming PC and higher-range workstations
PSU 700-900W Gaming PC and top-performance workstations
PSU more than 1000W Crypto mining PCs, servers

While the usual weapon of choice for gaming PCs are 600W or 750W power supplies, standard office will be perfectly happy with 400W or 500W PC power supply. You can read more about this in our article on how to build a PC, where you will find all the dos and don'ts of how to build a new PC, should you find the courage to build your PC on your own. If you trust experts more, we can build your dream machine for you.

Power Supply – ATX, SFX and TFX – What's the Difference?

The format defines the dimensions of the power supply. The use of different formats is tied with different PC case sizes. The four main types are:

  1. ATX standard format used in most desktop PCs
  2. SFX  smaller-size PC format, especially used for Mini-ITX PC Cases.
  3. TFX  is an alternative PC power supply format used in small PC setups with ATX connectors.


See the power supply unit accessories section for power surge protection, backup power supplies and more useful accessories.

Efficiency of Power Supply

The efficiency parameter determines how much power is lost due to heat and how much power is sent to the components of your PC. 80 PLUS certification indicates which PC power supplies are 80 % and more efficient. The table below shows efficiency with the respective degrees of power load.

Power load type Efficiency at 50% load Efficiency at 100% load
80 PLUS 85% 82%
80 PLUS Bronze 88% 85%
80 PLUS Silver 90% 87%
80 PLUS Gold 92% 89%
80 PLUS Platinum 94% 90%
80 PLUS Titanium 96% 94%

We recommend selecting your PC power supply according to its typical power load, which is usually 50 %. Power supplies with high efficiency will show the bigger difference in performance with high-power PCs used several hours non-stop daily.

What Connectors Can a PC Have?

Every PSU has input connectors that must correspond to the respective component on the motherboard. When buying, always look at the number of connectors required by your motherboard first, then search for the appropriate power supply.

  • CPU is used to connect the processor.
  • PCI-E connector is used to send power to the graphics card.
  • ATX is the main connector for the motherboard.
  • SATA connectors are for hard drives, SSDs and other drives.
  • Molex connector is used for fans or older formats of hard drives.


Want to use more graphics cards at the same time? Check that they are equipped with CrossFire or SLI technology and that you have a sufficient number of PCI-E busses.

Power Supply: Other Features

What other useful features can a power supply have?
  • Shut down button typical power on/off switch.
  • RGB lighting brightens up and adds up to your overall PC case's style.
  • Zero RPM mode stops the fan when cooling is not needed.
  • Heat-regulated fan speed adjusts the fan speed according to temperature to prevent overheating.
  • Passive cooling does not use a regular fan but mere air circulation. Used generally with less powerful power supplies.
  • Detachable cables allow you to connect only your selection of cables and thus help with cable management.

Many PCs are equipped with several failsafe solutions to help prolong their lifespan.

Power Supply Factor Correction (PFC) – What It Is and Why You Should Want It

PFC or power supply factor correction ensures levelling of the power consumption stream and the adjustment of the flow. The target is to prevent overloading or unbalanced power. There are two types of PFC:

  1. Active PFC uses a dedicated circuit to compensate, this is the more expensive variant, but a more effective solution.
  2. Passive PFC uses a more average capacity filter, which greatly reduces the cost, but also the quality of compensation.
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PC Power Supplies

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PC Power Supplies

Computer power supplies are standardized according to the ATX format, created in 1995 by Intel as a standard arrangement of components in computer cases. At that time, it replaced the older standard AT format. In 2003, Intel tried to replace it with BTX, but manufacturers did not switch to that format and instead ATX was revised several times. The latest and current versions are ATX2.2, and smaller formats mATX and Mini ITX.

As the ATX format developed, there were also changes in power supply - ie, in the area of computer resources. Therefore, it is now using ATX power supply for computer assembly versions 2.0, 2.2, 2.3 and 2.4 which differ in the main power connector, which plugs into the motherboard. It is therefore necessary for you to match the selected source to a version compatible with the motherboard.

When deciding which power source to buy, it is important to know the overall performance specification (given in watts and must be sufficient for the computer system - eg. For desktop computers 350-400 W is sufficient), cooling type and the amount and variation of additional power connectors.

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