HP Compaq NC4400 Maintenance And Service Manual page 109

Removal and Replacement Procedures
✎
The thermal paste should be thoroughly cleaned from the
surfaces of the heat sink 1 and processor 2 each time the heat
sink is removed. Thermal paste is included with all heat sink
and processor spare part kits.
Thermal Paste Locations
Reverse the above procedure to install the heat sink.
Maintenance and Service Guide 5–27