i am having this same issue with my 5.1 receiver, I have the HDMI plugged into my GTX 780 ti and it is reading the sound in the meter yet i cant hear anything through the speakers. my receiver works with my xbox and tv so i know it not the problem. Any Help?? Also when i turn the receiver on my screen blacks out briefly and also has caused my system to blue screen twice when the HDMI is un plugged i have zero issues. I really would like my surround sound My system specs are i7 4790k ASUS Maximus Hero 7 and ASUS GTX 780 ti OC windows 7