Dell Precision T7400 (Late 2007) - Manual (Page 240)

240 Adding and Replacing Parts
5 Disconnect the data cable from the back of the hard drive and from the
connector on the system board.
1 data cable 2 power cable
3 data cable 4 SATA connector on system board
5 optional SATA hard drive
NOTE: The optional fifth SATA hard
drive can be installed in any of the
5.25-inch drive bays.
1
2
4
5
3