Computer Dictionary of Information Technology

power supply unit

(PSU) An electronic module that converts high voltage (110 or 240 VAC) alternating current mains electricity into smoothed direct current at the various differnt voltages required by the motherboard; internal peripheral devices, cheifly storage devices: hard disks, CD or DVD, floppy disks and external connections such as USB. A PSU needs a high enough power output rating to supply all the devices connected to it and should output as little as possible electrical noise, both on the output wires and as electromagnetic radiation.

See also uninterruptable power supply.