Hi, I know this issue has been discussed at length on the forum but its a bit different in my case. I have a gtx 660 ti plugged in my mobo and use its hdmi port to my HDTV and everything was working fine until a week ago the display resolution changes to 800 x 600 of its own accord and now its stuck there. I have tried reinstalling the drivers but it doesnt work. I have also tried changing the slots and that has not worked either. The graphics card is sending out the display signal so I guess all the connections are working fine. So what else can be the problem? Please help me out asap.
Sounds like the GPU hdmi scaler has failed. Go into Nvidia control panel, scaling options, and change the scaling from GPU to display (or vice versa)