framerate error with 60fps games

[xexex]

I've noticed that on my pc all games that run at 30 fps run flawlessly (well, all the games that ppsspp can run well), but every single title I try that shows it should run at 60 fps runs at exactly 30 and the speed percentage remains stable at 50% speed. I think something must be wrong because my pc should be able to handle the 60 fps games at full speed (i7 930 at 3ghz, geforce 670 card). This seems to happen regardless of setting (I tried the defaults, playing with vsync on or off, playing with the frame limiting and frameskip options, nothing changes it). Does anyone have any guess what could be happening? And can you confirm that 60 fps games SHOULD be able to run at 100% speed with a decent pc? The fact that all 60 fps games stay at a perfect 30 fps 50% speed on my pc makes me think it must be some setting error. Any help would be very appreciated!

[xexex]

Actually I just fixed it and I thought I'd mention what I did in case anyone else has the same problem. I went to try a title in MAME and saw it was also running at a constant 50% speed (30fps in a 60fps game), so I knew it wasn't a ppsspp-specific issue. Recently I had tried enabling adaptive vsync through the nvidia control panel to improve performance in a recent game. When I turned that off everything went back to 60 fps!