Lenovo ThinkCentre M55e Hardware Maintenance Manual - Page 106

b. Do not drop anything onto the microprocessor socket while it is exposed. The socket pins must be kept as clean as possible. 16. On the new system board, release the lever securing the microprocessor retainer and then pivot the retainer until it is fully open. Note: There will be a black plastic cover on the microprocessor retainer to protect the socket on the new system board. Remove the black plastic cover and place it on the microprocessor socket of the failing system board when you complete this procedure. 17. Holding the microprocessor with your fingers, position the microprocessor so that the notches on the microprocessor are aligned with the tabs in the microprocessor socket on the new system board. Important To avoid damaging the microprocessor contacts, do not tilt the microprocessor when installing it into the socket. 18. Lower the microprocessor straight down into the system board socket of the new system board. 19. To secure the microprocessor in the socket, close the microprocessor retainer and lock it into position with the small handle. 20. Install the retention module for the heat sink and fan assembly on the system board. 21. Install the heat sink and fan assembly on the new system board. 22. Reconnect the heat sink and fan assembly cable to the system board. See the system board illustration for your machine type at "Identifying parts on the system board" on page 89. 100 Hardware Maintenance Manual