I have a 20 pin connector that connects to the motherboard and then I have a 4 pin (square) connector that connects to the motherboard. What does the 4 pin connector power. I'm trying to see if the PSU is any good. I have another PSU but it does not have the square 4 pin connector on it.from older unit and was going to see if I could try it out to power unit.
The 4-pin 12V ATX power connector (yellow and black wires) powers the processor on more recent motherboards. These motherboards will not boot if there is no power on that 4-pin connector. Processor will not power up. Old processors consumed less power. They were just powered from the +5V circuit on motherboard. Thus, old motherboards as well as old power supplies did not have the 4-pin 12V ATX power connector. Motherboards for newer high wattage processors (125-135W) usually have the 8-pin EPS 12V connector.
