I have same GFx and nearly same computer info as you.. I just have 4 gb ram insteed..
I jsut turned the Vsync off, and my fps is 250..
Try take some pictures and post here.. And let me have a look at your settings
well sometimes i got 250 too, problem is the fps isnt constant its range is like 100 - 300, which i have in new games, but as i read on some forums, there were guys with 600 - 1000 fps O.o, you want screen of my nvidia settings or of what?