What resolution? If you are running 1920x1080 you should be able to turn up all the settings on most games to max or near max. You don't have any bottleneck that I can see..
Also keep in mind some game developers have graphic settings higher than the game engine is designed to handle. Programs can improperly use your resources resulting in poor performance. I've never played minecraft.
the games im playing is, shogun 2, crysis 2 dx11+ high res, and bad company 2, usually at 1600x900.
bad company 2 should run great on max settings(I havent played on my 580 yet, but I ran it nearly at max w no AA just fine on my old Sapphire 5850. Shogun unfortunately you will still get slow down even on the 580GTX on max settings With 2 full armies(max size) on max graphics you will definitely see the 580GTX struggle, there are plenty of videos on you tube displaying just that.
(I have an i7 920 @3.4 and a 580GTX)
Theres a reason people still SLI/XF top end cards.
and advertising is advertising man. You will find low end video solutions that will say things like "extreme gaming performance!" using ambiguous terms. Its definitely misleading advertising but it isnt exactly false. i.e. It can run games blazing fast....like solitaire.