This is what I learned today. To get sound working over HDMI for a PC, you’ll need to get video card driver installed (since HDMI is technically on the video card) and the kicker is you need to have the correct display resolution in order for it to output sound. So, if you see an option for 1280 X 800 but the “recommended” is 1900 X 1080, you need to select the latter.
I just don’t get why the video card driver can’t have a little more intelligence in it – don’t display the resolutions that will not support both audio and video. And don’t let you see a HDMI sound option unless you’ve got the video card installed… Otherwise, there’s a lot of endless loops you’ll be sending people chasing after.