The power supply's job is to convert the power provided from the outlet into usable power for the many parts inside the computer case.
PSU (power supply unit), power pack, power converter
Motherboards, cases and power supplies all come in different sizes called form factors. All three must be compatible to work properly together.
Power supplies are not typically user serviceable. For your safety, it's usually wise to never open a power supply unit.
The power supply is mounted just inside the back of the case.
The side facing outside the case has a male, three pronged port that a power cable, connected to a power source, plugs into. There is also often a power switch and a power supply voltage switch.
Large bundles of colored wires extend from the opposite side of the power supply into the computer. Connectors at the opposite ends of the wires connect to various components inside the computer. Some are specifically designed to plug in to the motherboard while others have connectors that fit into fans, floppy drives, hard drives, optical drives, and even some high powered video cards.
Power supplies are rated by wattage to show how much power they can provide to the computer. Since each computer part requires a certain amount of power to function properly, it's important to have a power supply that can provide the right amount. The very handy Journey Systems Power Supply Calculator tool can help you determine how much you need.
