Computer power supply units (PSU) deliver the power to the PC hardware via a number of cables with connectors. Their generic specifications for various desktop systems are defined in Intel's design guides, which used to be periodically revised. Their latest standard is PSU Design Guide rev.2.0 released on June 2018. This document combines the requirements for ATX12V v2.52 and its five variations. Note that some brand name manufacturers did not follow Intel guidelines and used non-standard pinouts. Also see the information on new ATX12VO standard.

Standard ATX power supplies typically have the main power connector P1, additional 12V connectors, as well as peripheral, floppy drive, serial ATA, and PCI Express® receptacles, which we will describe below.