Western Digital WD Caviar Installation Manual page 13

3. Attach the computer system power supply cable to the 4-pin
power connector on the back of the Western Digital hard
drive. The 4-pin connector is keyed to ensure proper
insertion.
Attaching the IDE Interface Cable to the Motherboard
4. Single Drive Installation: Attach the end of the 40-pin IDE
interface cable from the Western Digital hard drive to the
IDE connector on the motherboard or controller card.
Dual Drive Installation: Connect the two hard drives
together by using a three-connector IDE interface cable.
Match pin socket 1 on the IDE cable (the marked wire) to
pin 1 on the motherboard or controller card.
Hardware Installation 9