If I install drivers that originally came with my graphics card (an Asus R9 290X), my DisplayPort and HDMI audio works perfectly fine. Version 15.201.1001.0
If I install any of the latest drivers on AMD's site, DisplayPort and HDMI audio stop working.
I keep my drivers somewhat up to date, and as of this past winter no new drivers detect the CF791's audio. A clean install of the latest Crimson Relive 17.6.1 or 17.5.2 does not help. When I installed 17.6.1, I noticed the HDMI audio driver is installed and the CF791 monitor is detected as an audio device, but the device manager says it's disconnected. Power cycling the computer or monitor has no effect.
A device manager screenshot is attached, you'll see the AMD High Definition Audio Device is clearly installed. However it thinks the audio device (Samsung CF791) is disconneced with the monitor attached via Displayport and HDMI audio simultaneously for troubleshooting. Typically I only run off of Displayport.
Audio works perfectly fine if I plug the monitor into the onboard Intel GPU, or use another computer (Macbook Pro) over HDMI or Displayport. So it's clearly the most recent AMD drivers, not the monitor.
Windows 10 x64 Professional
Asus R9 290x
Ivy Bridge CPU