Dell Precision WorkStation 420 Service Manual page 20

Figure 27. Microprocessor Replacement
To insert the new microprocessor/heat sink assembly into the system board connector, perform the following steps (this procedure assumes the
microprocessor removal procedure was just performed).
NOTE: Dell recommends that only a technically knowledgeable person perform this procedure.
CAUTION: Before you remove the computer cover, see
NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby
power LED on the system board has turned off. For the location of this LED, see
1. Press the processor firmly into its connector until it is fully seated.
You must use up to 25 lb of force to fully seat the processor in its connector.
2. Install the two large thumbscrews that secure the heat sink to the system board.
3. Replace the airflow shroud.
1 Airflow shroud
2 Thumbscrews (2)
3 Processor/heat sink assembly
4 Guide bracket
5 Second processor
1 Airflow shroud
2 Thumbscrews (2)
3 Processor/heat sink assembly
4 Guide bracket
5 Second processor
"Precautionary Measures"
Figure 22.