I recently upgraded to windows 10, first thing i noticed was all of my games were running slow. Initially i suspected Windows and disabled Xbox DVR etc etc. I found that everything runs fine after i reinstall the drivers but then again slow after restarts. Finally I found the issue : After I restart and look at the Overdrive Setting , I see that the GPU and Memory frequency are half of the default for the card. Since I was not overclocking, I never suspected this. I have a Saphire HD 7770 GHz Edition and default clock speed is 1000 MHz, but after I restart Windows, the upper limit of frequency becomes 500 MHz. If I "reset" in the overdrive settings, it goes back to 1000 MHz and the games run same as they were in windows 7.