Dell Precision 7920 Rack Owner's Manual page 53

Steps
1 To open the PCIe card holder latch, press the release tab.
2 To close the PCIe card holder latch, rotate the latch until it locks.
Removing expansion card riser 1
Prerequisites
1 If installed, remove expansion cards from the riser.
2 Disconnect any cables connected to the riser card.
About this task
NOTE: If installing a replacement expansion card riser 1 make sure the VROC key is transfered from the old card to the new card.
Removing and installing components 53