What Is the Power Supply for a Computer?

Computer power supplies power all the necessary components of the computer. The computer power supplies, commonly known as PSUs, come in various types and power levels, though most have the same general components. The type of PSU a computer requires depends on what components it has.

The Facts

A computer's power supply is a box that normally occupies the top space on the inside of a computer. The power supply is connected to an electrical outlet via a universal power cord and supplies power to components in the computer.

Features

The PSU consists of the power adapter, a fan and connector cables to different components. The power adapter can be converted via a switch in the back from 100-120V, which is used in North America and Japan, or to 220-240V, which is used in all other countries. The fan is used to cool the power supply and is normally on the bottom of the PSU. The PSU has connector cables to the motherboard, video cards and disk components, including hard drives and CD or DVD drives.

Types

There are three types of computer power supplies: AT, ATX and ATX-2. The main difference between the three is the number of connectors. An AT type power supply connects the front power switch of the computer directly to the power supply. An ATX power supply, however, requires the computer's power front power switch to be connected to the motherboard. The ATX power supply has extra connectors to the power board. A combination of these two components allows other hardware or software to power on the computer. ATX-2 PSU's are just like ATX power supplies, but they have additional connectors for more powerful motherboards and graphics cards.

Considerations

The various components of the computer determine what type of PSU is required. Different processors and graphics cards need different connectors from the PSU based on how advanced they are. Higher end graphics cards, processors and motherboards necessitate greater overall power from the computer power supply.

Misconceptions

A computer power supply with a higher output rating (measured by watts) is not always necessary. A PSU above 400W would only be necessary for intensive use such as in gaming, digital editing and video production. A 400W or less PSU is adequate for general use of a computer including web browsing, email and word processing. Using a higher watt computer power supply for basic tasks would only result in higher energy costs.