What did you have before? What FPS did you get before and what are you getting now? Where are you at when you look at FPS (I see a huge difference when out in the which vs. being in a city like Lions Arch).
To be honest I think GW2 is just not that efficient at utilizing the system. I have 2 570’s in SLI an i7-2700k @ 3.5GHz and barely get 60 FPS in the city – the system is barely even being used (30% CPU) with only 1 core tapped out.