24pin

24pin is the shorthand for the 24-pin ATX main power connector, the primary power input for modern computer motherboards. It carries the main power from the power supply to the motherboard and, in many systems, helps supply power to additional onboard components. The term is most closely associated with the ATX standard used in desktop PCs, though similar 24-pin arrangements appear in related power-supply standards such as EPS.

Historically, the original ATX standard used a 20-pin main power connector. As motherboard power requirements grew, the standard was updated to include a 24-pin header (often implemented as a 20-pin block plus a detachable 4-pin block, known as 20+4). This design allowed backward compatibility with older 20-pin boards while enabling greater current capacity and more signaling for newer boards.

The 24-pin connector provides multiple DC rails, including +12V, +5V, and +3.3V, along with standby power and control signals such as Power Good and PS_ON. Ground pins complete the circuit. The exact pinout is defined by the ATX specification and has minor revisions over time, but the general function is consistent: to deliver reliable power and essential signaling from the power supply to the motherboard. The connector is intended for use while the system is powered off or in a controlled state and is not designed to be hot-swapped.

Compatibility and variations include the common 24-pin ATX main connector found on most modern motherboards and power supplies, with some older boards able to accept a 20-pin input by omitting the 4-pin block. Server-oriented boards may use related EPS 24-pin configurations, often complemented by additional CPU power connectors.