Intel released the Pentium 4 processor series in 2000. The original series of Pentium 4 processors ran at speeds up to 1.5 GHz - significantly faster than products from the previous processor generation. The four-pin auxiliary power connector on motherboards exists to satisfy the demands of the Pentium 4 and subsequent processors.
Background
The Pentium 4 processor requires up to 12 amps of power at 12 volts. The four-pin auxiliary connector supplies 12-volt power directly to the processor, ensuring that the processor receives a consistent supply of power required for stable operation. Although it may be possible to run a Pentium 4-based computer with the four-pin auxiliary connector removed, doing so can result in instability and system crashes.
Purchasing a Power Supply
When you purchase a power supply, compare the number of pins on the main ATX connector to those on the motherboard you plan to use. The motherboard's main ATX power port may have 20 or 24 pins. In addition, the motherboard may have a four-pin or eight-pin auxiliary port for the processor as well as other connectors for PCI Express or AGP Pro video cards. Purchase a power supply with connectors matching the ports on the motherboard. If you are unsure about compatibility, Intel and AMD both maintain lists of tested and certified power supplies that you can reference.
Alternative
If you have a motherboard with a four-pin auxiliary power port and do not own a power supply with a matching connector, you may be able to use a standard four-pin device power cable instead. A four-pin device cable has four wires - one red, two black and one yellow - and typically has a white plastic connector on the end. This type of connector is also called a "Molex" connector. Like the four-pin auxiliary power connector, a Molex connector delivers 12-volt power. Purchase a Molex-to-P4 adapter to attach a Molex connector to your motherboard's auxiliary power port.
Connecting
A four-pin auxiliary power connector is "keyed" to prevent incorrect installation. When looking at the motherboard power port, you'll see that the edge of the port has a raised tab, allowing the release lever on the side of the power connector to lock in place. The lever and tab must face the same direction. Push the connector into the port firmly until the release lever clicks.
Tags: four-pin auxiliary, auxiliary power, four-pin auxiliary power, power connector, power port