ATX & EPS Power Supply Pinouts
Power Connectors & PCB Packages · 7 specs
Direct Answer
Desktop PC power supplies deliver multi-rail DC power under Intel ATX12V and EPS12V standards through standardized Molex Mini-Fit Jr. connectors: 24-Pin ATX Main (+3.3V, +5V, +12V, -12V, +5VSB, PS_ON#), 8-Pin EPS12V CPU (+12V), and 6+2 Pin PCIe auxiliary power.
Source: Intel ATX12V Desktop Power Supply Design Guide v2.52 / EPS12V Server System Infrastructure · Last reviewed Aug 28, 2026
Specs
| Governing Standards | Intel ATX12V v2.52 / EPS12V v2.92 / SSI Specification / Molex Mini-Fit Jr. 4.2 mm pitch |
| 24-Pin ATX Mainboard Connector | Delivers +3.3V (Orange), +5V (Red), +12V (Yellow), Ground (Black), +5VSB Standby (Purple), PS_ON# (Green) |
| 8-Pin EPS12V CPU Connector | 4× +12V pins (Yellow) + 4× Ground pins (Black) | Maximum capacity: 336W (28A at 12V using 18 AWG) |
| 6+2 Pin PCIe Graphics Connector | 3× +12V pins + 5× Ground/Sense pins | Rated for 150W (8-pin) or 75W (6-pin configuration) |
| PS_ON# Activation Pin | Pin 16 on 24-pin (Green wire) | Short to any Ground (Black) to manually turn power supply on |
| PWR_OK (Power Good) Signal | Pin 8 (Gray wire) | Outputs +5V when internal voltages stabilize within ±5% tolerance (100–500 ms) |
| Standard Wire Gauges | 18 AWG minimum for main lines (16 AWG on high-wattage Gold/Platinum units) |
Standard 24-Pin ATX Mainboard Power Connector Pinout Matrix
| Pin | Wire Color | Voltage / Signal Name | Pin | Wire Color | Voltage / Signal Name |
|---|---|---|---|---|---|
| 1 | Orange | +3.3V DC | 13 | Orange (Brown sense) | +3.3V DC (+3.3V Sense) |
| 2 | Orange | +3.3V DC | 14 | Blue | -12V DC |
| 3 | Black | Ground (COM) | 15 | Black | Ground (COM) |
| 4 | Red | +5.0V DC | 16 | Green | PS_ON# (Power Supply On) |
| 5 | Black | Ground (COM) | 17 | Black | Ground (COM) |
| 6 | Red | +5.0V DC | 18 | Black | Ground (COM) |
| 7 | Black | Ground (COM) | 19 | Black | Ground (COM) |
| 8 | Gray | PWR_OK (Power Good) | 20 | NC / White | Reserved (formerly -5V) |
| 9 | Purple | +5VSB (Standby +5V) | 21 | Red | +5.0V DC |
| 10 | Yellow | +12.0V DC | 22 | Red | +5.0V DC |
| 11 | Yellow | +12.0V DC | 23 | Red | +5.0V DC |
| 12 | Orange | +3.3V DC | 24 | Black | Ground (COM) |
EPS12V (CPU) vs PCIe (GPU) 8-Pin Incompatibility Warning
Although 8-pin EPS12V CPU and 8-pin PCIe power plugs look similar, their wiring polarity and mechanical pin keying are opposites:
- 8-Pin EPS12V CPU: The 4 pins closest to the clip latch are GROUND; the 4 bottom pins are +12V.
- 8-Pin PCIe GPU: The top pins are +12V; the bottom pins are GROUND.
- Safety Feature: Chamfered and square pin housings prevent cross-insertion, but forcing a PCIe plug into a CPU socket will dead-short the +12V rail directly to ground.