Suddenly, about a week ago, the front (CPU) fan in my Optiplex 960 SFF began to run at full speed all the time. I ordered a new air temp sensor, installed it, but the fan is still at full speed. The CPU temperature is around 92F. The BIOS setting is still at default (no check in the box). Does the fan need to be replaced? Or is there another fix, because the fan is noisy.