I'm not sure about the stutters most of the games run about 60 FPS constantly though sometimes it dips with too much detail.
There are only few games that run 60fps, all games I have run 30fps and some are stuttering as a bonus. Dead or alive, Burnout, Ridge racer are 60 fps games what I'm aware..games I have, PGR3, tombraider, FN3, Condemned, are 30fps