Dell Precision 7920 Owner's Manual page 22

CAUTION: Do not pull the connector by the cable wires. Instead, disconnect the cable by pulling on the connector end.
Pulling the cable wires may loosen them from the connector.
5 Remove the two screws securing the fan chassis to the system [1], and the two screws securing the fan chassis in front of the system
[2].
22 Removing and installing components