Dell Inspiron M511R (Mid 2011) - Manual (Page 81)

Processor Module 81
When the processor module is properly seated, all four corners are aligned
at the same height. If one or more corners of the module are higher than
the others, the module is not seated properly.
CAUTION: To avoid damage to the processor, hold the screwdriver perpendicular
to the processor when turning the cam screw.
3 Tighten the ZIF socket by turning the cam screw clockwise to secure the
processor module to the system board.
4 Follow the instructions from step 3 to step 16 in "Replacing the System
Board" on page 67.
CAUTION: Before turning on the computer, replace all screws and ensure that no
stray screws remain inside the computer. Failure to do so may result in damage to
the computer.