Dell Vostro 3888 Service Manual page 56

Steps
1. Remove the screw (#6-32) that secures the front I/O-bracket to the chassis.
2. Slide and remove the front I/O-bracket from the chassis.
3. Disconnect all the cables that are connected to the system board.
4. Remove the eight (#6-32) and (M2x4) screws that secure the system board to the chassis.
56 Disassembly and reassembly