Dell Precision 7920 Rack Owner's Manual page 62

CAUTION: To ensure proper system cooling, the PSU blank must be installed in the second PSU bay in a non-redundant
configuration. Remove the PSU blank only if you are installing a second PSU.
Installing power supply unit blank
Install the power supply unit (PSU) blank only in the second PSU bay.
Align the PSU blank with the PSU slot and push it into the PSU slot until it clicks into place.
Removing AC power supply unit
Prerequisite
CAUTION: The needs one power supply unit (PSU) for normal operation. On power-redundant systems, remove and replace only
one PSU at a time in a system that is powered on.
1 Disconnect the power cable from the power source and from the PSU you intend to remove, and then remove the cable from the
strap on the PSU handle.
Step
Press the release latch and slide the PSU out of the system by using the PSU handle.
62 Removing and installing components