This section provides instructions on how to replace the system board.

CAUTION:

The heat sink and microprocessor might be very hot. Turn off the computer and wait three to five minutes to let the computer cool before removing the computer cover.

Note: Before replacing the system board, make sure you have a retention module for the new system board.

To replace the system board, do the following:

1. Remove all media from the drives and turn off all attached devices and the computer. Then, disconnect all power cords from electrical outlets and disconnect all cables that are connected to the computer.
2. Remove the computer cover. See "Removing the computer cover".
3. Remove the front bezel. See "Removing and reinstalling the front bezel".
4. Place the computer on its side to gain easier access to the system board.
5. Remove the PCI card holder. See "Removing and reinstalling the PCI card holder".
6. Remove the optical drive and the optical drive bracket. See "Replacing the optical drive".
7. Remove all memory modules and PCI cards that are currently installed. See "Installing or replacing a memory module" and "Installing or replacing a PCI card".
8. . Remove the heat sink and fan assembly from the failing system board. See "Replacing the heat sink and fan assembly".
9. Remove the microprocessor from the failing system board. See "Replacing the microprocessor".
10. Remove the battery from the failing system board. See "Replacing the battery".
11. Remove the front fan assembly from the computer. See "Replacing the front fan assembly".
12. Note the location of all cable connections on the system board and disconnect all cables. See "Locating parts and connectors on the system board".
13. Remove the three screws (1) that secure the memory chiller frame. Remove the three screws (2) that secure the other memory chiller frame. Then, remove the two screws (3) that secure the black cable clip.

14. Remove the six screws that secure the system board to the chassis.

Figure 1. Removing the six screws that secure the system board to the chassis

15. Carefully lift the failing system board out of the chassis.
16. Position the new system board into the chassis so that the screw holes in the new system board are aligned with those in the chassis. Install the six screws that secure the system board to the chassis.
17. Reinstall the two memory chiller frames and the black cable clip by tightening the eight screws to secure them to the system board.

18. Remove the microprocessor socket cover from the new system board.
19. Install the memory modules, PCI cards, battery, microprocessor, and heat sink and fan assembly that you removed from the failing system board to the new system board.
20. Connect all cables to the system board. See "Locating parts and connectors on the system board".
21. Go to "Completing the parts replacement".

The failing system board must be returned with microprocessor socket covers to protect the pins during shipping and handling. Install the microprocessor socket covers removed from the new system board on the failing system board.

Note: The microprocessor socket cover installation procedure should be performed on both microprocessor sockets on the failing system board.

To install a microprocessor socket cover:

1. Release the lever securing the microprocessor retainer and open the retainer to access the microprocessor.
2. Grasp the microprocessor on the sides and lift it straight up and out of the socket. Do not touch the contacts on the microprocessor socket.
3. Align the notches (1) of the microprocessor socket cover with the alignment keys (2) of the microprocessor socket. Lower the socket cover straight down into the microprocessor socket on the system board.

Note: Your microprocessor socket and cover might look slightly different from the illustration.

4. Carefully press the socket cover straight down until it is secured into the socket.

5. Lower the microprocessor retainer and then lower the lever to secure the retainer. Make sure the lever is securely locked into position.