HP ProDesk 400 G1 Maintenance And Service Manual page 141

5. Disconnect the fan cable from the system board connector labeled CPUFAN (1), and then lift the
heat sink from atop the processor (2).
When reinstalling the fan sink, make sure that its bottom has been cleaned with an alcohol wipe and
fresh thermal grease has been applied to the top of the processor.
CAUTION: Fan sink retaining screws should be tightened in diagonally opposite pairs (as in an X) to
evenly seat the fan sink on the processor to avoid damage that could require replacing the system
board.
Make sure to replace the fan duct. Failure to install the fan duct may cause the computer to overheat.
Fan sink
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