I have a Dell Studio XPS 8000 with a Intel core I7 CPU 860 at 2.8ghz and 16 gigs ram, Nvidia GTX 260 and want to upgrade to a Nvidia GTX 760. I am running windows 7 ultimate. One of the Games I have some graphics issues with is Civ 5 Brave new world when moving around map it lags and as game progresses it lags even more on game speed. How much would that graphics card upgrade help me in speed and refresh rate etc. I am also running raid 0 and have an overall windows performace rating of 5.9 but that seems to be based on hard drive speed everything else is 7.4 or 7.1 at the lowest. All advice is welcome please. I am disabled vet use computer a lot for entertainment like gaming.