What does a Power Supply Unit (PSU) convert?

A Power Supply Unit (PSU) primarily converts Alternating Current (AC) into Direct Current (DC). This is essential because most computer components, such as the motherboard, graphics card, and hard drives, operate on DC power. The PSU takes the AC electrical power from the outlet—typically provided at a voltage of 110V or 220V—and transforms it into a lower voltage DC output, which is safe and suitable for the internal components of a computer system.

The need for a PSU is critical in ensuring that the electronic devices can perform optimally while receiving the correct type of power. The conversion process also involves regulation, where the PSU maintains stable voltage levels despite fluctuations in the input or differing loads in the components that it powers.

This makes the selection of this answer particularly appropriate as it directly addresses the primary function of a PSU in a computer setting, highlighting the necessary transition from AC to the required DC format for effective operation of hardware components.