Dell Precision T7400 (Late 2007) - Manual (Page 259)

Adding and Replacing Parts 259
5 Disconnect the other end of the interface cable from the system board
connector labeled "USB." To locate system board connectors, see "System
Board Components" on page 27.
6 Slide the sliding-plate lever to the right to release the shoulder screw and
slide the drive carrier out of the drive bay.
1 interface cable 2 Media Card Reader connector (USB)
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2