Try other HDMI audio drivers:
- ATI HDMI audio driver 5.00.7000.09 included in Catalyst 9.12 (ATI Catalyst Suite). Select only HDMI audio in custom installation.
- Realtek driver R2.39 for "ATI HDMI Audio Device".
Try to play 8 Channel test file.
That link is broken. But the Samsung will have an EDID extension block with NO HD audio capabilities, so it won't work for the Onkyo. You'll need to grab at least your AVR EDID and use that.
Anyway it seems you've already modified the registry to have that Samsung EDID, right?
Can you post that link again to see what you did?
Onkyo PR-SC885p.txt 2.91015625k . file
No luck, ATI HDMI Output still "Not plugged in."
My Onkyo is set to DVD as input 1 and that is where the HTPC is connected.
TX-NR906_MOD.zip 1.1640625k . file
I had a similar problem with my Denon. The final solution was to plug the monitor/TV DIRECTLY into the video card and then boot up. I then powered down and re-connected the Denon and ATI HDMI Output was fine. Really strange but it worked. (Maybe the ATI saves something on the card??) It's worth a try since it's relatively easy.
One additional point: in my case, the monitor also showed "No signal" during boot-up and the first part of Windows start-up until the login screen (which appeared normally). Once I did the procedure above, the boot-up screens re-appeared.
Try switching to other HDMI ports on the Onkyo. If that doesn't work either then it's definitely a problem of your Onkyo pre-pro not syncing at all with the ATI.
Try then applying the modded EDID override that I attach to this post. Or simply go ahead and purchase a Gefen HDMI or DVI Detective Plus.
Solo EDID's for 885p and Samsung 8000.zip 2.421875k . file
Cloned Display Mode with HDMI Audio Working.zip 2.380859375k . file