HP DC7800 - Manual (Page 185)

4. Connect the cable to the rear of the optical drive (1), and then slide the drive the rest of the way
into the bay so that it locks in place (2).
Optical Drive Connector
1. Prepare the computer for disassembly ( Preparation for Disassembly on page 159 ).
2. Remove the computer access panel ( Computer Access Panel on page 163 ).
3. Remove the optical drive ( Removing the Optical Drive on page 170 ).
4. Push the top of the connector down through the opening of the hard drive cage until the connector
is on the opposite side of the hard drive cage opening.
5. Pull the connector straight up to disconnect it from the system board.
To install the optical drive connector, reverse the removal procedures.
Optical Drive Connector 173