Extremely low performance sapphire 7850

Hey all. I have an ati 7850 and a 4.2ghz quad core CPU and the benchmark for guild wars 2 says with that I should be getting 60-70 fps with auto-detect settings which is everything on high. But even on low I never go passed 30-40fps, high is 15-30 fps. And that's just in questing zones not WvWvW.

I have seen youtube videos of people with the same GPU as me and the game runs much better, also the brand is sapphire and I overclocked it even more than it already is. any ideas?