HP Nc6400 - Compaq Business Notebook Maintenance And Service Manual page 141

Removal and Replacement Procedures
✎
The thermal paste and thermal pads should be thoroughly
cleaned from the surfaces of the heat sink 1, processor 2,
Chip1 3, and Chip2 4 each time the heat sink is removed.
Thermal paste and thermal pads are included with all heat sink,
processor, and system board spare part kits.
Thermal Paste and Thermal Pad Locations
Reverse the above procedure to install the heat sink.
Maintenance and Service Guide 5–41