I have the same graphic card and having a frame issue aswell. It turned out my gpu keeps going to about 100 degrees c every time i play GuildWars 2. It will be fine the first hour or 30 min(running at 30-60 fps) then it starts to overheat(runs at 5-10 fps). I can run team fortress 2 , left 4 dead 2 and other games fine. I don’t know what the problem is.