Dell OptiPlex 3070 Tower Service Manual page 68

6. Disconnect the following cables from the system board:
a. CPU power [1]
b. Hard drive data and optical drive data [2]
c. Speaker [3]
d. System power [4]
e. SATA [5]
7. To remove the system board:
a. Remove the screws that secure the system board to the computer [1].
68 Removing and installing components