Apple PC Compatibility Card - Manual (Page 101)

17 Plug the other end of the SCSI audio cable into the connector labeled “REV_SND_OUT”
(Reversed Sound Out) on the PC Compatibility Card.
The Reversed Sound Out connector is in the upper-left corner of the card, the
third connector from the end.
Route the cable between the PC Compatibility Card and the processor card,
and toward the front of the interior as shown.
Connector labeled “REV_SND_OUT” on the PC Compatibility Card
Route the cable so that it passes between the
processor card and the PC Compatibility Card. Route the cable around the
front of the computer’s interior.
Processor card
101 Installing the Card in a Power Macintosh 8600 or 9600