Im getting 50-75 fps on gw2 with same card stock. Maybe u got it plugged in wrong pcie port or somthing else like processor or ram is bottlenecking it. Maybe u got a crappy card
And thats with every single setting maxed. 8gb of Cas 8 ram, i53570k stock, windows 8, msi gd65
And now with i5-3570k at 4.5ghz and sapphire 7970 ghz 3gb at 1200/1600 i get about 100 -120 on gw2 on ultra in 1080p. my 3dmark is p10225. I have noticed drops to 30 but that was because of bad clocks and crashed drivers, reboot your pc. Also download latest windows updates and sapphire drivers and catalyst 13.2 beta and mobo bios ect.