...Also, what is the temp on the card? It will slow down a lot if the temp gets too high.
Really? Aren't GPU's built to withstand 90-100C heat without affecting performance?
My experience with the 5770's is that at some point they slow down due to the heat... That is somewhere north of 80C when that happens, my Mh/s rate dropped like a stone, it was reproducible on my cards... once I drop the temp down no more problems. Might just be my model of the 5770's... but I wouldn't want to run a card that hot 90+C for very long.