Re: Gtx 480 as primary sound card FTW.
GF100 GPUs(GTX 480, 470, 465) have a built-in HD audio processor like the GT21x GPUs(210, GT 220, 240) that outputs 8 channel LPCM, supports 24bit 192kHz output.
GF104/106/108 GPUs also have a built-in HD audio processor with 8 channel LPCM output but also has the ability to bitstream Dolby TrueHD and DTS-HD MA straight to the receiver without decoding it first, instead letting the receiver do the decoding.
The onboard audio on your motherboard is totally unused, it is not processing anything because the HD audio processor in the GPU does it. Please don't spread misinformation, gerardfraser.