Is it PC -> HDMI -> AVR -> HDMI -> TV? If so, do you see the same problem PC -> HDMI -> TV?
What’s your player of choice? If you’re stuck w/ WMP/WMC your only real options is to use Reclock.
Otherwise, XBMC’s sync renderer + audio features (have you tried WASAPI?) is a good option.
Unfortunately, the root cause is probably the dGPU.
