I connect my AMD Radeon HD 7970 graphics card to my hdtv with hdmi to hdmi cable, and I get no sound from my computer. I've checked under Control Panel/Sound and it says "realtek hdmi output, not plugged in." It is plugged in there is video but no audio, i tried a different hdmi cable, and tried different hdtv, but still no sound. I can't change realtek hdmi output to default device since it thinks the cable is unplugged. I don't know how to make it work, I just got this computer today, and I think it came with all the latest drivers. My laptop gets Sound and Video from hdmi cable but not my desktop computer. How do I get my tv speakers to play sound?