ATX Power Supply Pinout Diagram and Connector (20, 24 Pin)

You will be hearing about the ATX power supply when it comes to the power supply system of the computer, PC, or desktop. The Power supply unit(PSU) of the computer generates power in different voltage and current and it supplies to the different hardware through different wires, connectors, and cables. Generally, the Switched Mode Power Supply or SMPS system is used to provide electrical power to the different components or hardware of the computer. The ATX Power supply system is used to generate the main three types of voltage such as +3.3V, +5V, and +12V. It also generates the -5V DC, +5V Standby voltage, and -12V supply.

ATX Power Supply Pinout Diagram

Here, you can see the pinout diagram for the ATX power supply with its every voltage and color identification.

You can see here two versions of the ATX power supply are shown - version 1.0 consists of 20 pins whereas version 2.0 consists of 24 pins. Actually, the motherboard is supplied by the 20-pin connector that is version 1.0 but in the latest version 2.0, the -5V is removed and an extra four pins are added to provide the additional power to the CPU. So the combination of the old 20 pins and an additional four pins developed version 2.0. In the old version 1.0, the -5V was used to supply the ISA Bus. As in the modern PC system, the ISA bus is removed the -5V is also not required.

The connector is connected to the four different wires that have special features such as,

+3.3V

There are three nos +3.3V connections in the version 1.0 connector and four nos +3.3v connections in the version 2.0 connector. The main function of this connection is to sense the voltage drop in the power supply wiring.

+5VSB or +5V Standby

Standby power means it will always be available even when all other power supplies are turned off. This is used to power up the device or component that actually controls the main power supply.

PWR_OK

It is also known as "Power Good". It is an output terminal from the power supply source. It helps to indicate that the supply voltage is normal or stabilized and it is ready to use. So it is to be connected to any LED or light or any indication system.

PS_ON# or Power On

It is used to pull up the signal from the load to the source or from the motherboard to the power supply. It is used to ensure that the load is connected to the power source. Once the power started being delivered from the power source to the motherboard this connection started pulling back a small power.

In the 24-pin connector, you will see,

• 4 nos +3.3V pins
• 8 nos Common Pins
• 1 no -12V pin
• 5 nos +5V Pins
• 2 nos +12V Pins
• 1 not connected
• 1 PWR_OK
• 1 PS_ON#
• 1 no +5VSB or Standby Voltage pin

In the 20-pin connector, you will see,

• 3 nos +3.3V pins
• 7 nos Common Pins
• 1 no -12V pin
• 4 nos +5V Pins
• 1 nos +12V Pins
• 1 no -5V
• 1 PWR_OK
• 1 PS_ON#
• 1 no +5VSB or Standby Voltage pin

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