HP Compaq nc4010 - Notebook PC Maintenance And Service Manual page 113

Removal and Replacement Procedures
✎
Each time the heat sink is removed, any thermal grease residue
should be carefully cleaned from the heat sink 1 and processor
surfaces 2, and new thermal grease should be applied to both
surfaces.
Removing the Thermal Grease From the Heat Sink and Processor
Reverse the above procedure to install the heat sink.
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