24-pin ATX12V 2.x

ColorSignalPin PinSignalColor
Orange+3.3 V113+3.3 VOrange
+3.3 V senseBrown
Orange+3.3 V214-12 VBlue
BlackGround315GroundBlack
Red+5 V416Power onGreen
BlackGround517GroundBlack
Red+5 V618GroundBlack
BlackGround719GroundBlack
GreyPower good820-5VWhite
Purple+5 V standby921+5 VRed
Yellow+12 V1022+5 VRed
Yellow+12 V1123+5 VRed
Orange+3.3 V1224GroundBlack

20-pin ATX connector omits the last four pin: 11, 12, 23, 24)

Pins 8, 13, and 16 are control signals:
- "Power On" is pulled up to +5V by the PSU, and must be driven low to turn on the PSU.
- "Power good" is low when other outputs have not yet reached, or are about to leave, correct voltages.
- "+3.3 V sense" line is for remote sensing of the voltage drop in the power supply wiring (should be connected to the +3.3 V on the motherboard)

"+5 V standby" supplies power even when the rest of the supply lines are off.

Pin 20 (-5V, white) is absent in current power supplies; it was optional in ATX and ATX12V ver. 1.2, and deleted as of ver. 1.3.


ATX Aux Power Cable

PinColorFunction
1BlackGround
2BlackGround
3BlackGround
4Orange+3.3 V
5Orange+3.3 V
6Red+5 V


ATX 4pin +12V Power Cable

ColorFunctionPin PinFunctionColor
BlackGround13+12 VYellow
BlackGround24+12 VYellow

ATX 8pin EPS +12V Power Cable

ColorFunctionPin PinFunctionColor
BlackGround15+12 VYellow
BlackGround26+12 VYellow
BlackGround37+12 VYellow
BlackGround48+12 VYellow

You can plug an 8pin EPS cable into a 4pin 12V motherboard.
You also can plug a 4pin 12V power cable into an 8pin EPS motherboard connector but there's no guarantee that it will work.


6/8pin PCI Express Power Cable

   

ColorFunctionPin PinFunctionColor
Yellow+12 V15GroundBlack
Yellow+12 V26GroundBlack
Yellow+12 V37GroundBlack
BlackGround48GroundBlack

6 pin connector maximum wattage delivery: 75 Watt
8 pin connector maximum wattage delivery: 150 Watt



ATX Tolerance

VoltToleranceRangeRipple max
+5 VDC±5% (±0.25 V)+4.75 V to +5.25 V50 mV
-5 VDC±10% (±0.50 V)-4.50 V to -5.50 V50 mV
+12 VDC±5% (±0.60 V)+11.40 V to +12.60 V120 mV
-12 VDC±10% (±1.2 V)-10.8 V to -13.2 V120 mV
+3.3 VDC±5% (±0.165 V)+3.135 V to +3.465 V50 mV
+5 VSB±5% (±0.25 V)+4.75 V to +5.25 V50 mV