20. Lift the right side of the system board, and lift the board (with heat sink assembly and left I/O board) up at an angle to remove it from the baseassembly.21. Remove the M2 x 3-mm screw securing the left I/O board to the system board.22. Disconnect the left I/O board from the system board by pulling the two boards apart, separating the connectors.Replacing the System Board Assembly1. Connect the connector on the left I/O board to the connector on the system board.2. Replace the M2 x 3-mm screw to secure the left I/O board to the system board.3. Lower the left edge of the left I/O board into the left side of the base assembly, aligning the connectors with their corresponding holes in the baseassembly.4. Lower the system board (with heat sink assembly and left I/O board) onto the alignment pins in the base assembly.1 guide pins (2) 2 system board3 base assembly 4 heatsink assembly1 screw 2 system board3 left I/O board connector 4 left I/O board5 heatsink assemblyCAUTION: Before working inside your computer, read the safety information that shipped with your computer. For additional safety bestpractices information, see the Regulatory Compliance Homepage on www.dell.com at: www.dell.com/regulatory_compliance.NOTICE: Ensure that any loose cables do not get caught beneath the system board.