This connector is pretty much standard with any computer peripheral. You will notice it mainly on floppy drives, hard-drives, tape drives and in some cases, a fan.

This is what it looks like if you are looking at a cable coming FROM a power supply.

If you want the pinouts for the connector on the peripheral, reverse the order. To be sure, use a volt meter.

1    +5VDC
2    Ground for +5VDC
3    Ground for +12VDC
4    +12VDC