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