Dell Precision T7610 (Late 2013) - Manual (Page 52)

Power Supply Unit (PSU) Lock
The PSU lock prevents the removal of the PSU from the chassis.
NOTE: To lock or unlock the PSU, always ensure that the cover of the chassis is removed. For information on
removing the air tunnel (if available), see Removing the air tunnel (if available).
To secure the PSU, remove the screw from the unlock screw location and tighten the screw to the lock location.
Similarly, to unlock the PSU, remove the screw from the lock screw location and tighten the screw to the unlock screw
location.
52