I setup the system (CPU, memory, HD, etc) and installed Vista Ultimate; the system worked great and no problems- until yesterday. The system would boot up and video would display but I was not getting any audio. My receiver indicated a 'HDMI PCM' signal, but no sound. Windows indicated sound was being output (via the audio indicator bars in the sound properties) but no combination of volume/outputs/tweaks would get it to work!
I finally started looking around the ATI Catalyst menus for audio properties- but found none. I did notice that my resolution had changed from 720p to 800x600 (not sure how/why that happened). When I changed my resolution back to 720p the audio started working again! I will have to assume that the video card will only provide audio out when there is a HD signal being sent out?