ATX 24-pin Pinout
Main motherboard power connector supplying +3.3 V, +5 V, +12 V, standby, and control signals.
Overview
The 24-pin ATX main power connector is the primary motherboard supply defined by the Intel ATX12V spec (the 24-pin form arrived with ATX12V 2.0). It delivers +3.3 V, +5 V, +12 V, -12 V, +5 V standby plus PS_ON# and PWR_OK.
Pins are two rows of 12. Pin 13 (+3.3 V Sense) feeds 3.3 V regulation back from the board. PS_ON# (pin 16) is pulled low to turn the supply on; PWR_OK (pin 8) goes high when rails are stable.
Pinout
| Pin | Name | Function | Description |
|---|---|---|---|
| 1 | +3.3V | SIGNAL | +3.3 V rail |
| 2 | +3.3V | SIGNAL | +3.3 V rail |
| 3 | COM | GND | Ground |
| 4 | +5V | SIGNAL | +5 V rail |
| 5 | COM | GND | Ground |
| 6 | +5V | SIGNAL | +5 V rail |
| 7 | COM | GND | Ground |
| 8 | PWR_OK | POWER | Power Good status output (high when rails in spec) |
| 9 | +5VSB | SIGNAL | +5 V standby (always on while AC present) |
| 10 | +12V1 | SIGNAL | +12 V rail |
| 11 | +12V1 | SIGNAL | +12 V rail |
| 12 | +3.3V | SIGNAL | +3.3 V rail |
| 13 | +3.3V Sense | SIGNAL | +3.3 V remote sense (thin wire) |
| 14 | -12V | SIGNAL | -12 V rail |
| 15 | COM | GND | Ground |
| 16 | PS_ON# | POWER | Power-on control (active low) |
| 17 | COM | GND | Ground |
| 18 | COM | GND | Ground |
| 19 | COM | GND | Ground |
| 20 | Reserved/NC | SIGNAL | Reserved (was -5 V pre-2004) |
| 21 | +5V | SIGNAL | +5 V rail |
| 22 | +5V | SIGNAL | +5 V rail |
| 23 | +5V | SIGNAL | +5 V rail |
| 24 | COM | GND | Ground |
Notes
- Pin 20 is unused/reserved on modern supplies; it carried -5 V on legacy boards.
- The 24-pin splits as 20+4 to power older 20-pin boards.
- Pin 13 is a remote sense line, not a current-carrying rail.
Reference: Intel ATX12V Power Supply Design Guide· verified 2026-06-27