Control the fan speeds of your CPU/GPU and Chassis fans based on varying temperature readings from your system.
SpeedFan Home Page
SpeedFan is freeware.
SpeedFan monitors voltages, fan speeds, and temperatures.
SpeedFan can dynamically adjust fan speeds based on changing computer temperatures.
SpeedFan runs on Windows 9x, ME, NT, 2000, 2003, XP, Vista, and 7.
SpeedFan also has 64-bit support.