Cooling Fan - Dell Precision WorkStation 420 Service Manual

4. Rotate the power supply back into position, making sure that the securing tab snaps into place.
5. Replace the computer cover, and reconnect your computer and peripherals to their power sources and turn them on.
NOTE: After you remove and replace the cover, the chassis intrusion detector will cause the following message to be
displayed at the next system start-up:
ALERT! Cover was previously removed.
6. Enter System Setup and confirm that the top line in the System Data area correctly identifies the installed processor(s).
7. While in System Setup, select System Security, and reset Chassis Intrusion to Enabled or Enabled-Silent.
NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting
the chassis intrusion detector.
8. Run the Dell Diagnostics to verify that the new microprocessor is operating correctly.

Cooling Fan

Figure 28. Cooling Fan Removal
To remove the cooling fan, perform the following steps.
CAUTION: Before you remove the computer cover, see
1. Remove the computer cover.
2. Rotate the power supply.
3. Squeeze in on the two pairs of tabs on the airflow shroud and lift it away.
4. Disconnect the fan power cable from the FAN_SYS connector (see
5. Gently pull on the plastic locking tab, and slide the fan toward the power supply to disengage the four latching tabs holding the fan to the back
of the chassis (see Figure
Battery
Figure 29. Battery Removal
28).
1 Fan power cable
2 Fan
3 Plastic locking tab
"Precautionary Measures"
Figure 22 for location).