Dell Precision 420 - Manual (Page 85)

To replace the computer cover, perform the following steps:
1. Check all cable connections, especially those that might have come loose during your work. Fold cables out of the way so that they do not
catch on the computer cover. Make sure cables are not routed over the drive cage —they will prevent the cover from closing properly.
2. Check to see that no tools or extra parts (including screws) are left inside the computer's chassis.
3. Facing the left side of the computer, hold the cover at a slight angle as shown in Figure 7 , and then align the top of the cover with the top of
the chassis.
4. Insert the three hooks on the cover into the three recessed slots on the computer chassis so that the tabs catch the hooks inside the slots.
5. Pivot the cover down toward the bottom of the chassis and into position. Make sure the securing hooks at the bottom of the cover click into
place.
Figure 7. Replacing the Computer Cover (Mini Tower Chassis)
6. If you are using a padlock to secure your system, reinstall the padlock.
7. Reset the chassis intrusion detector by entering the System Setup program and setting Chassis Intrusion to Enabled or Enabled-Silent.
Removing and Replacing the AGP Card Brace (Mini Tower Chassis Only)
To access any expansion cards in the mini tower chassis, you must first remove the accelerated graphics port (AGP) card brace that secures an
AGP card in the AGP socket.
1. Remove the computer cover as instructed in " Removing the Computer Cover (Mini Tower Chassis) ."
2. Remove the screw securing the AGP card brace to the chassis (see Figure 8).
Figure 8. Removing the AGP Card Brace
1 Hook
2 Recessed slot
NOTE: After removing and replacing the chassis, the chassis intrusion detector causes the following message to be displayed at
the next system start-up:
ALERT! Cover was previously removed.
NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting
the chassis intrusion detector.
CAUTION: Before you remove the computer cover, see " Safety First —For You and Your Computer ."