HP ProBook 4430s, 4431s, 4330s and 4331s Notebook PCs - Maintenance and Service Guide

Heat sink
All heat sink spare part kits include replacement thermal material.
Description Spare part number
Heat sink for use in computers with discrete graphics 646356-001
Heat sink for use in computers with UMA graphics 646357-001
Before removing the heat sink, follow these steps:
1. Shut down the computer. If you are unsure whether the computer is off or in Hibernation, turn
the computer on, and then shut it down through the operating system.
2. Disconnect all external devices connected to the computer.
3. Disconnect the power from the computer by first unplugging the power cord from the AC outlet,
and then unplugging the AC adapter from the computer.
4. Remove the battery (see
Battery on page 48).
5. Remove the bottom door (see
Bottom door on page 50).
6. Remove the fan (see
Fan on page 67).
Remove the heat sink:
1. Position the computer upside-down with the front toward you.
2. To remove the discrete heat sink, in the order indicated, loosen the six captive Phillips screws
(1) — (6) that secure the heat sink to the system board.
3. Lift the heat sink up and out of the computer (7).
4. To remove the UMA heat sink, in the order indicated, loosen the four captive Phillips screws (1)
— (4) that secure the heat sink to the system board.
Component replacement procedures 69