Alright I have a Gigabyte motherboard (GA-MA790x-UD4P) with HD Audio (ALC 889a) and a NVidia 9400gt video card that I'm trying to pass sound through from my motherboard. I've got a HDMI cable connected to the back via the DVI adapter that came with the video card, but I'm not able to get any sound and all indications show that is sound being played. However if I use the analog jacks with my headphones it works fine.
I've tried using the original audio drivers and video drivers and the latest ones available from Nvidia, Gigabyte, and Realtek. I have also tried to simply use the optical s/pdif out, but again no sound and additionally I don't even see the light from the jack generally associated with an optical out.
Also I've checked bios to ensure the on board audio is enabled and upgraded bios to the latest release.
Also I'm running Win 7 x64, volume is set to 100%, Realtek Digital Output is set to default, and my Nvidia control panel shows my setup as HDCP compatible with audio enabled.
I'm trying to cover all my bases here and solve this before I try to RMA my motherboard back to Gigabyte because I'm beginning to think I just have a faulty motherboard and I'd rather not go without my computer for a while.
DVI does not normally pass audio, just video, though there are exceptions. Without knowing which specific card you have we cannot continue along this path.
If your video card does not have an HDMI port, and it doesn't sound like it does or you would have used it LoL, then I suggest you use an optical cable from the PC to TV as the cheapest route; otherwise upgrade your video card.
i have the same board and have just ennabled pass through successfully - assuming you have the special SPDIF input bracket and it is plugged in of course. When it is pluged in and functioning the realtek/gigabyte sounnd mixer app loads the following data. Status - Lock Sampling rate PCM 48Khz (in this case) data validation - valid copy protection - Copy Free. It is coming in on an optical TOS Cable and goes out on a Coax on the top yellow phono output. I can then get it on my A/V Amp when playing films etc. but what I rally want is to be able to process the signal from AAC and retransmit as AC3 or analog direct as i have an old amp.