Dell OptiPlex 7020 (Mid 2014) - Manual (Page 30)

4. Slide the intrusion switch toward the bottom of the chassis and remove it from the computer.
Installing the Intrusion Switch
1. Insert the intrusion-switch into the chassis rear and slide it outward to secure it.
2. Connect the intrusion-switch cable to the system board.
3. Install the:
a. heat sink assembly
b. cover
4. Follow the procedures in After Working Inside Your Computer.
Removing the System Board
1. Follow the procedures in Before Working Inside Your Computer.
2. Remove the:
a. cover
b. front bezel
c. optical drive
d. drive cage
e. memory
f. expansion card(s)
g. heatsink assembly
h. power supply
i. processor
3. Disconnect all the cables connected to the system board.
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