I recently got my HTPC up running. But i"m bit confused about the audio/video connection. What should I do with the S/PDIF port on the mobo? Is there a use for it now that I can just connect my HDMI cable from 5770 (support bitstream) to my onykia 670 receiver, which in turn connect to my 46" inch TV using HDMI cable as well? I'm using a tv tuner as well.
I would like to play blu-ray at the highest quaility.
If you're using a Radeon HD5770 and streaming both video and audio over HDMI, then you don't need the onboard S/PDIF port on the motherboard. Plus, the HD5770 as you pointed out will bitstream HD audio while S/PDIF can only output lossy DD/DTS audio so you'd want to use the HD5770 audio for the best audio (assuming your receiver supports HD audio).