lag problem with 8800gt

Hello guys. I have a problem : I am using amd athlon 6000+ in ASUS m3a78-eh board and coolermaster 500w power sup, Asus 8800gt 256 bit 1gb graphics card.
My System is Lagging when im playing a game. If i play counter strike by opengl, it lags but if i play with d3d no lag. Its happening on many games Actually it doesnt happen in Hitman 4 but happens in Knight Online plz help me

so this have nothing to do with cuda development.
Perhaps may you use some different settings for openGL oder d3d in the driver tab, like default AA or such things.