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What Is A Computer Power Supply?

A computer power supply unit, or PSU, is the component that supplies power to a computer. A power supply is designed to convert 100-AC power from the power mains to usable low-voltage DC power for the internal components of the computer. Some power supplies have a switch to change voltage, while others have automatic sensors.

The most common computer power supplies are built to conform with the ATX form factor. Specifications of the ATX standard enables different PSUs to be interchangeable with different components inside a PC. ATX power supplies also are designed to turn on and off using a signal from the motherboard, and provide support for modern functions such as the standby mode available in many computers. For laptops, see Laptop Batteries to find a compatible product.

How to Choose A PSU

Most desktop power supplies are the same size and fit in most cases, excluding some small form factor cases. Your total components will dictate the amount of wattage you need for your power supply, although having extra doesn’t hurt and allows for later expansion if needed.

There are four different types of power supplies. Modular, Non-Modular, Semi-Modular and Fully Modular.

Modular: These cables are detached from the power supply and are plugged in. The advantage of Modular power supplies is that you have better control over your cables.

Non-Modular: These cables are built into the power supply and they are static and cannot be moved. The benefit is they are generally cheaper than most modular PSUs of the same quality.

Semi-Modular: Some cables are built in with others being detachable. For some brands you can buy the cables to meet the size requirements you need for the cables, much like full-modular.

Fully-Modular: All cables are detachable.

Recent Customer Reviews

Solid workhorse
"hI bought and installed this power supply almost 5 years ago. It has met all my needs and still runs well with no issues. Colors are cool and runs quietly."
-Travis Hirshlor,  March 31, 2017
Ultra HS650
"had it for little over 3 years works great .like the fact that the wires not attached to the unit so you can use only what you need"
-AHMAD ALKHATB,  Feb 5, 2017
Universal ATX PSU Tester
"This tester is great and saves a lot of time when trouble shooting computer issues."
-Mark Henderson,  Oct 19, 2016
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