My Enermax "Whisper" power supply has been a torn in my ear since day one. The supposedly quiet temperature controlled fan screamed like an 8000 RPM Delta!
Tonight had had the idea to try mucking about with the thermistor circuit. Obviously, an addition or subtraction of resistance should change the fan speed. To my delight, I I discovered that an increase in resistance dropped the fan speed. Thus, simply cutting the wire to the thermistor leads to minimum fan speed.
So, if you have a whisper that driving you nuts with it's loud fan, don't hesitate to snip off the thermistor. Your ears will thank you.