HP PROBOOK 4520S Maintenance And Service Manual page 90

4. Clean the thermal material from the surfaces of the heat sink components (1) and (3) and from the
system board (2) and (4) when the heat sink is removed. Replacement thermal material is
included with all heat sink, system board, and processor spare part kits.
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For computers with UMA subsystem memory on the system board, follow these steps:
1. Position the computer right-side up with the front toward you.
2. Following the sequence stamped into the heat sink, loosen the four screws (1), (2), (3), (4)
around the processor.
80 Chapter 4 Removal and replacement procedures