Lenovo ThinkCentre A51p Hardware Removal And Replacement Manual page 11

2. Remove the four screws at the rear of the chassis.
3. Rotate the drive bay assembly upward to gain access to the system board.
4. Disconnect all power supply cables from the drives and the system board.
Remove the cables from the cable clips and ties. See Figure 1 on page 5.
Note: Take note of the locations of the power supply cables.
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Replacing customer replaceable units (CRUs)
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