Originally Posted by cpzlcu
I uninstalled drivers > CCleaner > Reboot.
In the meantime I tried IGPU and MB HDMI output too, but I got the same supported formats.
I switched back to the GTX 1080 HDMI and reinstalled the 368.81 drivers with clean install.
Nothing changed about the supported formats, instead now I'm missing 20bit depths and 88/176/192Khz sample rates that I had before reinstalling the drivers.
Since you are having the issue even with the IGPU with the MB HDMI, I am leaning toward a HDMI EDID issue. I know you mentioned the receiver is an Onkyo but what TV/Display are you using? Reason I am asking is because I was having the same issue as you. The reason you are getting only the non HD audio formats is possibly because your HTPC is picking up your TV/Display (which will only do Dolby Digital and DTS) versus your Onkyo (which can do everything). My solution to the problem was introduce a HDMI splitter coming out of the receiver going to the TV/Display. Once I did this, my HTPC now showed the HD Audio formats and my receiver now showed DTS HD MA and Dolby True HD.
Hope this help you.......
Denon AVR-3311CI, Denon DVP-602CI, B&K Reference 200.7 S2, Belkin PF60
Sony BDP-S5000ES, Silverstone HTPC (6 Tuner DVR & 10 TB Media)
PSB Stratus Minis, PSB Stratus C6, PSB Alpha S surround, James Subwoofer EMB-1200
Sharp LC-70LE755U, Harmony 880 Remote