Dell Dimension E521 - Manual (Page 47)

Place the system board assembly that you just removed next to the replacement system board to ensure it is identical.
Installing the System Board
1. Gently align the board into the chassis and slide it toward the back of the computer.
2. Using the six screws, secure the system board to the chassis.
3. Install the heat sink assembly bracket and secure using the two green screws.
4. Replace the cables that you removed from the system board.
5. Replace the memory modules into the memory sockets at the same locations from which you removed them (see Installing Memory ).
6. Replace the processor (see Installing the Processor ).
7. Install the heat sink assembly:
a. Place the heat sink assembly back onto the heat-sink assembly bracket.
b. Rotate the heat sink assembly down towards the computer base and ensure that the two captive screws are properly aligned with the holes in
the system board.
c. Tighten the two captive screws.
8. Replace any add-in cards on the system board.
9. Replace the computer cover (see Installing the Computer Cover ).
10. Connect your computer and devices to an electrical outlet, and turn them on.
11. Verify that the computer works correctly by running the Dell Diagnostics (see Dell Diagnostics ).
Installing the Computer Cover
1 system board 2 heat sink assembly bracket 3 screws (8)
NOTE: The heat sink bracket assembly must be properly oriented to allow proper installation of the heat sink assembly.
NOTICE: Ensure that the heat sink assembly is correctly seated and secure.
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions located in the Product Information Guide.