ATX 24-Pin Mainboard Power Connector

The 24-pin master connector that delivers 3.3 V, 5 V, 12 V and -12 V from the PSU to the mainboard. Universal since 2003.

The ATX 24-pin connector is the master power feed from the PSU to the mainboard. It evolved from the original 20-pin ATX (1995) and was extended in 2003 to deliver more current on the 12 V rail for PCI Express. Today every desktop and many server mainboards use the same connector. The classic split into 20+4 pin allows a single PSU cable to fit both legacy 20-pin and current 24-pin boards - the extra 4-pin block simply detaches.

Technical Specifications

Standard	ATX12V v2.x / ATX 3.0
Pins	24 (formerly 20+4)
Voltages	+3.3 V, +5 V, +12 V, -12 V, +5VSB, PWR_OK, PS_ON
Connector type	Molex Mini-Fit Jr.
Pin pitch	4.20 mm
Polarisation	Asymmetric, latching clip
Typical current	up to 24 A on +12 V

Matching products in the shop

ATX power supplies
ATX 24-pin extension cables
PSU adapters

Frequently Asked Questions

Can I use a 20-pin PSU on a 24-pin mainboard?

Technically yes if total current draw stays within the 20-pin limit - but most modern PCs (especially with PCIe GPUs) need the additional 12 V rails of the 24-pin connector. Use a 20+4 cable or upgrade the PSU.

What is PWR_OK / Power Good?

Pin 8 - the PSU asserts this signal high (~5 V) only when all rails are within tolerance. The mainboard waits for PWR_OK before releasing the CPU from reset.

ATX 3.0 changes?

ATX 3.0 (2022) keeps the 24-pin form factor but adds the 12VHPWR (16-pin) connector for GPUs up to 600 W and tighter transient spec for 12V.

Related connectors in the glossary

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