I have an HIS 6870 that the fan speed keeps getting stuck on. I go into the cataylst center and will up the fan speed to 50% when im gaming. A lot of the times when im done and want to lower the speed down to 25% for when the computer is just sitting there it wont let me. I will move the adjustment and it just does nothing until I reboot. It doesnt happen everytime, but enough to be quite annoying.