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What is the wire color coding of ATX computer power supplies ?

Computer power supplies (PSU) convert AC to low-voltage regulated DC power. Most modern desktop computers conform to the ATX standard, which supplies three positive rails: +3.3V, +5V and +12V.

Wires coming out of an ATX PSU are color-coded as follows:

Yellow: +12V
Red: +5V
Orange: +3.3V
Black: Ground

Purple: 5V SB (standby voltage)
Green: /PS_ON (it can be shorted to ground to start PSU)
Grey: PWR_OK (status signal generated by PSU to indicate voltages are OK)
White: -5V (optional on newer ATX-2 PSUs)
Blue: -12V

  User Reviews/Comments:
by vidcorp - 2020-01-21 10:30
Do I need a load resistor on an older Dell power supply that does not have a (Brown) Sensing wire? I will be using this for a bench power supply.
by anonymous - 2021-07-01 09:54 need a 10 ohm *5 or more watt* power resistor from +5 to ground, or
the converter board from allelectronics that converts atx to all standard voltages
for around 15-20 dollars...
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