Dell Precision T7400 (Late 2007) - Manual (Page 237)

Adding and Replacing Parts 237
8 Connect the power cable to the drive.
9 Connect one end of the data cable to the hard drive.
10 If you are using a add-in storage controller card, the other end of the data
cable is attached to the add-in storage controller card.
Otherwise, connect the data cable to a HDD connector on the system
board.
NOTICE: Ensure that you connect hard drives only to connectors on the system
board that are marked HDD. Do not connect hard drives to connectors labeled
SATA. (The exception is a SATA boot drive in a five-drive configuration.)
1 power cable 2 data cable
3 HDD connector
3
1 2