Dell Precision T5400 (Late 2007) - Manual (Page 282)

282 Adding and Replacing Parts
5 Use a long Phillips screwdriver to loosen the four captive screws on the
sides of the heat-sink assembly.
CAUTION: The heat-sink assembly may become very hot during normal operation.
Ensure that it has had sufficient time to cool before you touch it.
6 Lift to remove the heat-sink assembly from the computer.
7 Disconnect the optional speaker connector (if installed) from the system
board.
8 Disconnect the card fan from the system board connector labeled
FAN_CCAG (see "System Board Components" on page 28.)
1 heat sink assembly 2 captive screw housing (4)
2
1