My specs are i7, GT540M (2GB), 8GB RAM DDR3, with additional 24" monitor HDMI.
So when I play CSGO I set the settings to low on everything to get more FPS and I change the resolution into 4:3 with 1024 x 768 then I get 50-80 fps with avg. 62-70fps
(Yes the graphic's quality quite bad)...