Dell GX280DT - GX280 Desktop Computer User Manual page 155

1 mini-tower system board
2 screws (10)
11. Place the system board assembly that you just removed next to the replacement system board to ensure it is identical.
Replacing the System Board: Small Form-Factor, Small Desktop, and Small Mini-Tower
Computers
1. If your original system board uses a mounting plate rather than a tray to attach to the chassis, replace the existing system board with the replacement
system board:
a. Slide the system board assembly toward the back of the computer, attaching it to the hooks on the floor of the chassis.
b. Replace the retention screw at the front of the computer.
1 retention screw
2 hooks (4)
2. If your original system board uses a metal tray rather than a mounting plate to attach to the chassis:
a. Detach the system board from the metal tray:
Remove the screw that secures the original board to the metal tray.
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Remove the four mounting screws from the heat-sink retention base, and then remove the system board by sliding the board back and
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detaching it from the hooks on the metal tray.