Pinout of the PC Internal Power Connectors

PC Power Connectors (used inside the pc case)
There are two main power connectors used within the PC. These are used to provide power to a whole range of drives and additional internal peripherals. These include floppy disk drives, hard disk drives, CD/DVD Drives and tape streamers. They use a connector called a Molex for the larger drives and a mini molex for smaller ones , in particular the floppy disk drive.

3.5" Floppy Disk Drive Connector

Pin	Name	Color	Description
1	+5V	Red	+5 VDC
2	GND	Black	+5 V Ground
3	GND	Black	+12 V Ground (Same as +5 V Ground)
4	+12V	Yellow	+12 VDC

4 pin Mini Molex Connector

5.25" Floppy Drive / Hard Disk Drive and Misc Peripheral Connector

Pin	Name	Color	Description
1	+12V	Yellow	+12 VDC
2	GND	Black	+12 V Ground (Same as +5 V Ground)
3	GND	Black	+5 V Ground
4	+5V	Red	+5 VDC

4 Pin Molex
Connector