Case Fan runs a full speed

How is the fan installed?
Taking power directly from the PSU? Or plugged into the motherboard fan headers?

Or are you saying that before yesterday your fan was running at a slower speed but is now only running at full speed?

The fan is plugged into the mother board. The fan was running at a slower speed but now its full out. The only time I've ever noticed fan noice was when I was putting a heavy gaming load on my system or having 10 or so IE open at the same time. Thanks for you help.

Are you using a gpu app, or say Sandra, or especially Everest or maybe EVGAs precision?. Sometimes Ive seen where 1 of these apps activate fan control by just reading fan rpm, maaybe a bios glitch

No I'm not running any app, I will review the Bios thanks.