HP PAVILION 311 Maintenance And Service Manual page 79

Removal and replacement procedures
Remove the system board:
1. Remove the Phillips PM2.0×7.0 screw 1 that secures the power connector to the base enclosure.
2. Release the power connector 2 from the base enclosure.
3. Remove the Phillips PM2.0×4.0 screw that secures the system board to the base enclosure.
Maintenance and Service Guide 4–39