Dell Precision 3431 Service Manual page 102

6. Remove the heat sink with fan:
a) Disconnect the heat sink fan cable from the system board [1].
b) Loosen the four captive screws that secure the heat sink [2] and lift it away from the system [3].
NOTE: Loosen the screws in a sequential order (1,2,3,4) as mentioned on the system board.
102 Installing the USB Type-C card