Zotac puts Audio over HDMI on NVIDIA 8800 Card
 

The lads did not have the fully functional high-end boards at Games Convention 2007, but after a week of hard work, engineers managed to change the complex reference 8800 PCB and squeeze in room for an S/PDIF connector and routing to a DVI port. This means that Zotac's 8800GTX AMP board now has support for DVI Audio.

And there is only one reason why you'd need DVI Audio. That reason is connecting that ugly yellow DVI-HDMI adapter, offering full HDMI connectivity from top to bottom (8800GTX to 8400GS).

http://www.theinquirer.net/default.aspx?article=42139