HDMI Audio Out: Same for ATI and NVIDIA?

[wildfire99]

I've pretty much decided on merits and need which card to go with, the GTX280 or the 4870x2. However one last thing is bugging me. How is the HDMI output on each, particularly HDMI audio? The ATI's of course have a special bullet point that they support 7.1 output, however I've seen support for HDMI audio on the GTX series as well. Is there a difference between the two cards or will they output audio the same? Is there any advantage on the red side right now for HTPC duty?

 

[rennyf77]

nvidia card audio support acts as a pass through for the audio chip on your motherboard or sound card. it requires that you connect a header from the spdif jumper to the video card. the ati card is not a pass through and is in and of itself, an audio device.

 

[wildfire99]

I assume that means (via S/PDIF's limited bandwidth) that the NVIDIA solution is 2 channel only, whereas the ATI solution is fully 7.1 since I can set it as my "sound card" in say, PowerDVD? Does that also apply for games, if I wanted 5.1 output via HDMI? How does that impact OpenAL/EAX (geez, this is complicated already) if I'm transporting decoded/processed audio from say, an X-Fi over the video card?

 

[Nenu]

Not if the soundcard supports DDLive, 5.1 over optical/spdif.
NVidias cards do not support 7.1 channels over HDMI.

To get EAX 5.1 over digital you need a Creative Titanium or Auzentech Prelude.