Dell OptiPlex 755 - Manual (Page 234)

b. Gently lift the heat sink from the processor.
c. Lay the heat sink down on its top, with the thermal grease facing upward.
5. Pull the release lever straight up until the processor is released, and then remove the processor from the socket.
6. Unpack the new processor, being careful not to touch the underside of the processor.
7. If the release lever on the socket is not fully extended, move it to that position.
8. Orient the front and rear alignment-notches on the processor with the front and rear alignment- notches on the socket.
9. Align the pin-1 corners of the processor and socket.
10. Set the processor lightly in the socket and ensure that the processor is positioned correctly.
11. When the processor is fully seated in the socket, pivot the release lever back toward the socket until it snaps into place to secure the processor.
1 top of heat sink
2 heat sink
3 retention base
4 release tab
NOTICE: Unless a new heat sink is required for the new processor, reuse the original heat sink assembly when you replace the processor.
1 center cover latch
2 processor cover
3 processor
4 socket
5 release lever
NOTICE: Ground yourself by touching an unpainted metal surface on the back of the computer.
NOTICE: When replacing the processor, do not touch any of the pins inside the socket or allow any objects to fall on the pins in the socket.
NOTICE: To avoid damage, ensure that the processor aligns properly with the socket, and do not use excessive force when you install the processor.