A power supply is a device that provides power to a computer server. It is typically a large, rectangular box with a number of cables coming out of it that are used to connect to the various components of the server, such as the motherboard, hard drives, and other peripherals. The power supply converts AC power from the wall outlet into the DC power that the server requires to operate. It also regulates the voltage and current to ensure that the server receives the correct amount of power. The power supply is an important component of a computer server as it ensures that the server has a stable and reliable source of power.