ATX 24 pin power supply connector pinout

ATX 2.2 and later (ATX12V 2) is common ATX standard, 24 pin connector.

Changes to ATX standard were made to support 75 watt PCI Express requirements. Most power is now provided on 12 V rails and the power on 3.3 V and 5 V rails was significantly reduced. The standard specifies that two independent 12 V rails (12 V2 for the 4 pin connector and 12 V1 for everything else) with independent overcurrent protection are needed to meet the power requirements.

New ATX v 2.2 uses new connector, but most motherboards nowdays allow to use an old ATX v 1.x power supply with ATX 20 pin connector - it connects to 24 pin motherboard receptacle.

 

Pin	Name		Color	Description
1	3.3V		Orange	+3.3 VDC
2	3.3V		Orange	+3.3 VDC
3	COM		Black	Ground
4	5V		Red	+5 VDC
5	COM		Black	Ground
6	5V		Red	+5 VDC
7	COM		Black	Ground
8	PWR_OK		Gray	Power Ok is a status signal generated by the power supply to notify the computer that the DC operating voltages are within the ranges required for proper computer operation (+5 VDC when power is Ok)
9	5VSB		Purple	+5 VDC Standby Voltage (max 10mA, max 2A in ATX 2.2 spec)
10	12V		Yellow	+12 VDC
11	12V		Yellow	+12 VDC
12	3.3V		Orange	+3.3 VDC
13	3.3V		Orange	+3.3 VDC
14	-12V		Blue	-12 VDC
15	COM		Black	G
16	/PS_ON		Green	Power Supply On (active low). Short this pin to GND to switch power supply ON, disconnect from GND to switch OFF.
17	COM		Black	Ground
18	COM		Black	Ground
19	COM		Black	Ground
20	-5V		White	-5 VDC  (this is optional on newer ATX-2 supplies, it is for use with older AT class expansion cards and can be omitted on newer units)
21	+5V		Red	+5 VDC
22	+5V		Red	+5 VDC
23	+5V		Red	+5 VDC
24	COM		Black	Ground

  /PSON activated by pressing and releasing the power button while the power supply is in standby mode. Activating /PSON connects the power supply's /PSON input to ground, thereby switching the power supply to full-on condition.

18 AWG is recommended for all wires except pin 11, which should be 22 AWG. For 300W configurations 16 AWG is recommended.