What's your current storage medium? I'm guessing your using a HDD? If so which exact model is it?
Also how much RAM do you have?
Just did some quick google searches - and it appears EVGA might have had some problems with certain 6XX series cards.
Apparently some/certain drivers are working better than others.
Also reading that upgrading your BIOS appears to help as well.
For now you might want to check out these other threads with similar problems:http://forums.nvidia.com/index.php?showtopic=226227&st=1340http://www.evga.com/forums/tm.aspx?high=&m=1629304&mpage=1#1629355
One last thing - apparently someone upgraded to an SSD from a HDD and their stuttering disappeared.