Anybody seen this before? I recently built a new HTPC and everything was working perfectly at first. Then on XBMC I started getting random red pixelation on screen during playback (not in XBMC menus etc). Now its starting to happen in WMC as well but only in TV so far, not in Media Browser. I've googled the issue and it seems others have had it with PS3.
If thats the case it would be strange as its just the onboard G630 which runs pretty cool. Also the box itself is in the basement and is well ventilated. I'll have a look at the temps under load though.
OK I think I figured out the problem. It is a LCD tv and other inputs didn't have any pixelation so it was indeed an HDMI issue. I use a monoprice HDMI over Cat5e extender between the receiver and the TV. The receiver unit of this device was overheating as it had fallen against the back of the TV. Re-mounting it against the cooler wall seems to have eliminated the pixelation.