ATX 24-pin 12V Power Supply Pinout

Pinout for the Standard ATX 24-pin 12V Motherboard Power Connector

The ATX 24-pin power supply connector is the standard motherboard power connector in computers today. The connector itself is a Molex 39-01-2240 connector, often called a Molex Mini-fit Jr.

ATX 24-Pin 12V Power Connector Pinout (ATX v2.2)

Below is the complete pinout table for the standard ATX 24-pin 12V power supply connector as of Version 2.2 of the ATX Specification (PDF).

If you're using this pinout table to test power supply voltages, be aware that the voltages must be within ATX specified tolerances.

Pinout Reference
Pin Name Wire 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_ON Gray Power Good
9 +5VSB Purple +5 VDC Standby
10 +12V1 Yellow +12 VDC
11 +12V1 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 Ground
16 PS_ON# Green Power Supply On
17 COM Black Ground
18 COM Black Ground
19 COM Black Ground
20 NC White -5 VDC (Optional - Removed in ATX12V v2.01)
21 +5V Red +5 VDC
22 +5V Red +5 VDC
23 +5V Red +5 VDC
24 COM Black Ground

The pinouts for the 15-pin SATA Power Connector, 4-pin Peripheral Power Connector, 4-pin Floppy Drive Power Connector, and for other ATX power supply connectors can be seen in our ATX Power Supply Pinout Tables list.

More Information on the ATX 24-Pin 12V PSU Connector

The power supply connector can only be plugged in while pointing a specific direction on the motherboard. If you look carefully at the following illustration, you can see the pins take a unique shape, one the motherboard matches in only one direction.

Illustration of an STX 24 pin power supply connector
Lifewire / Alex Dos Diaz

The original ATX standard supported a 20-pin connector with a very similar pinout as the 24-pin connector but with pins 11, 12, 23, and 24 omitted. This means the newer 24-pin power supply is useful for motherboards that require more power, and therefore eliminates the need for ATX 12V power supplies to provide an auxiliary power cable (although some still may).


How to Manually Test a Power Supply With a Multimeter

24-Pin & 20-Pin Compatibility

The additional four pins are usually detachable (see the lower part of the image above), allowing it to be used on a 20-pin motherboard connection. The extra pins simply hang over the motherboard connector—they don't plug into another slot. Some motherboards allow the reverse: to use the older 20-pin power supply cable on a 24-pin motherboard connection.

If you need to use a 24-pin power supply connector on a motherboard that only accepts a 20-pin cable, there are a number of online retailers where you can purchase a 24-pin to 20-pin adapter, like this StarTech adapter from Amazon. Although the motherboard appears to accept all 24 pins using this type of adapter, it still means the additional four pins go unused.

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