Why You Needs the Computer Power Supply Unit (PSU)?

The computer power supply unit converts AC power from the domestic electrical service (power from a wall outlet) to the specific DC voltages that require by the computer components to operate correctly. So, if you want a reliable, crash-proof system, use a high-quality power supply.


The power supply unit is usually located at the back of a computer tower case. Four-metal screws hold the power supply to the case. The power supply often mounts on rails inside the case, next to a large hole in the back panel of the case that provides access to the AC power connector and the exhaust fan from the back of the computer.
If you are looking inside the computer, the power supply unit is a metal box with several bundles of wires connecting it to the rest of the PC components (i.e. motherboard, hard drive, CD/DVD drives). Here is how the PSU look like:

The bundles of color-coded wires that come out of the power supply each have one or more standard power plugs that fit the power input sockets on the motherboard, the disk drives, the fans, and other components inside the computer's case. Each bundle of wires has a plastic connector at the end.
If you are specifying a high-spec PC with a powerful graphics card and CPU we recommend you opt for a high-end PSU, around the 600W+ region. Otherwise, a basic standard 350W PSU is sufficiently powerful and is very quiet. The power voltage is written on the cover of the PSU.
Most of the time, you do not need to buy a computer power supply unit separately when buying a new PC because it is bundled inside the case. If the standard power supply is appropriate, you may save a few bucks by buying the bundle. Otherwise, buy only the case and install a high-quality power supply sized appropriately for your needs. You need to get a new PSU when it's spoilt and need replacement.