HP Deskpro EN Supplementary Manual page 46

3. Raise the easy access drive bay to the upright position and
connect the flat ribbon cable to the system board.
Connecting the Flat Ribbon Cable
4. Return the easy access drive bay to the normal position and
connect the ribbon cable to the rear of the drive. (If you
have also installed an audio board on the computer, connect
the audio cable from the P7 connector on the system board
to the audio board.)
The ribbon cable is a multifunction cable that carries
power, audio, and data between the system board and the
CD-ROM drive.
Guide to Features & Upgrades 3-21