A computer power supply unit, or PSU, powers up all the components in a computer. Without it, a computer is of no use even if it is decked out with other top-of-the-line components. This box converts the AC power from the mains to a low-voltage DC that is suitable for a computer's internal parts.
Popular brands include Corsair, Antec, and XFX, although there are many more good manufacturers from which buyers can choose. Most users go for a hybrid modular unit as it is flexible and easy to manage. A PSU with this configuration has permanently attached as well as removable cables. On a full modular unit, all cables are removable, whereas on a non-modular unit, all the cables are permanently attached. The power rating on a PSU can range from 500 watts to over 1000 watts.