I know his problem. Even i had this. Buddy open the cooler of the Card and blow the air from ur mouth in the holes from where the air comes out. A fur ball will surely come out from the cooler which is clogging the cooler. Even my cards temps were 105 degrees at load at 100% fan speed. But now that i cleaned it. It is 52 degrees at LOAD at 50% FAN SPEED. Amazing isn't it?
Btw the sudden drop in FPS is due to the temps. Because the card throttles back at 100 degrees due to high temps. No need to RMA it. Because after a month or so the new card will get clogged soon. So either buy an after market cooler or keep cleaning the current cooler.

Btw i have order a cheap after market cooler for 500. After these my friend's cards temps were 45 degrees at load.

Mind u m in North India so temps can vary in ur place. PM me if u have any problems in cleaning up the cooler.