HP Compaq nx5000 series Maintenance And Service Manual page 140

Removal and Replacement Procedures
✎
Carefully clean any thermal grease residue from the underside
of the heat sink 1 and processor surfaces 2 each time you
remove the heat sink. Then apply new thermal grease to both
surfaces.
Removing the Thermal Grease from the Heat Sink and Processor
Reverse the above procedure to install the heat sink.
5–32 Maintenance and Service Guide