My setup is the following.
gigabyte p-55a ud3 motherboard
realtech onboard sound Acl892
msi gtx 580 twin frorz II
receiver is a denon avr 591
The two connection options I've attempted are hdmi from my video card to my tv and toslink to the reciever. Or hdmi to the reciever from the video card as my video audio out.
My issue is that I cannot for the life of me figure out how to get any true surround sound out of my receiver from my pc. I have tried both toslink and hdmi out. With toslink I can get PL II emulation across the board but that's it. No true 5.1 output from any applications/games that support it. I get true surround is from certain videos that have 5.1 hardcoded. I think. I'm in over my head here so I very likely am misinformed.
With hdmi using the GTX 580 all I get is multichannel in. I lose even the PL II emulation at that point. As far as I can tell the 580 is only outputting stereo. After extensive driver updates and searches through forums, spec sheets, and anywhere else I am thoroughly confused. If I understand correctly the 580 does not have the same audio capabilities via hdmi as other 500 and even 400 range cards and the realtech chip doesnt provide dts or dolby live which I would need to get 5.1 via toslink. So I think I need a soundcard or a video card at this point. Any education or corrections at this point would be vastly appreciated. I have become very aware during my research that I have no idea what I am doing.