Wierd FPS problem

Hi guys i came here to ask about my pc cuz i think i did everything and i can't seem to find the problem. I a'm playing guild wars 2 and many other games and i have this very weird problem about Framerates. When i play guild wars 2 i have an average of 40-60 FPS after i changed my card to 7870 OC ed. It was working fine like the whole time until today. I tried pulling out the hardwares and cleaning all the dust inside my pc. My pc is pretty clean cuz i always clean it every week. When i did this the problem was solved so i thought it was just a loose hardware. Then today the problem came back again so i tried my old method and it didnt work. So far i get as low as 5 fps in GW2 which is not right. FPS drops varies in every place so i thought it was Gw2 Problem. Then i played Medal of Honor Warfighter and Bf3 and some of my GPU/CPU intensive games and they all work fine. So now idk what's the problem and how to identify them. I run Memory diagnostic tool and no problems we're detected. My GPU/ CPU temp are at 40-60 idle/load. Need some help!

Specs
AMD 105tt 2.80ghz
Sapphire 7870 OC ed
4gb Gskill cl9 RAM
Gigabyte 880gm 3.0 mobo

Thanks guys!