Possible Athlon 64 dual core issue

[crobertsw27]

I recently upgraded all the major components of my computer. Before I upgraded I was able to play graphics intensive games without too many problems. After I upgraded and re-installed windows I got sketchy performance in 3D games. Most of the games will run way too fast and are made unplayable.
Is anybody else on this forum having similar issues with dual core CPU's? This issue happens no matter if the graphics are set to the lowest or highest resolution. I can set the affinity of the game to only one CPU core, but some games then run way too slow. Thanks.