is your cpu or gpu overclocked?how much memory is installed? what settings are you playing at? I have a gtx 650 overclocked in my spare rig(fx6300) and it plays fairly nice on the 64 bit version. your 650Ti on medium should play fairly well.
you should get some pictures of your cpu/ gpu load temps of both etc while gaming with say hwinfo
I would go to the nvidia geforece experience and make sure your drivers are updated and optimize the game from there