HP Z800 Maintenance And Service Manual page 198

7. Set the cold plate retention ring on the CPU heatsink mounting base, and then slightly tighten a
single retention screw (see Installing the CPU heatsink on page 201).
TIP: For convenience, start with the rear CPU.
Tighten the retention ring screw only one or two turns to keep its corner in place while allowing
the rest of the ring to move.
Figure 5-111
The retention ring screws
186 Chapter 5 Replacing components ENWW