When you start the PC, the gfx card fan spins fast until Ati CCC loads and its fan control steps in. This is normal. Mine acts the same way. The fan spins high until Starting Windows screen disappears.
If it happens again and again when there is even no load on the gfx chip, then you should check air flow in the case. Cable clutter may block free air circulation and result in localized abnormal temperature increases.
If cable management in the case is perfect, then fan control circuitry of the gfx card may have a defective component, such as a resistor or transistor, in it or fan itself may be defective.