It's not that big of a deal to loose as many FPS as you are talking about in 1 benchmark. A lot of things could have an affect..... a process started to run in the background, Too much heat, an odd driver shudder, and so on. I just wouldn't worry about the Difference in FPS between two Benchmarks. Now if you start seeing a steady decrease in FPS.... over a short period of time. Then yes there may be an issue. Or if you see some odd pixels.... then yes I would start to look into it. But just seeing a small decrease in score from one run to another.... don't worry. You will probably see as many increases in score for no reason as you do decreases.