HP Compaq Presario,Presario C300 Maintenance And Service Manual page 155

4. Turn the system board upside down with the USB ports
toward you.
5. Disconnect the fan cable 1 from the system board.
6. Remove the four Phillips PM2.5×7.0 screws 2 that secure
the heat sink to the system board.
Removing the Fan/Heat Sink Assembly Screws, Part 2
Maintenance and Service Guide
Removal and Replacement Procedures
5–61