SpeedFan is a program that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. info and show hard disk temperatures. SpeedFan can access digital temperature sensors and can change fan speeds accordingly, thus reducing noise. SpeedFan can find almost any hardware monitor chip connected to the 2-wire SMBus.
Speed Fan - Readings Fans, Speed, Temperature, Voltage
Speed Fan - Configure Set Speeds - Temperature vs Noise
Speed Fan - S.M.A.R.T. Tab - HDD Info
Speed Fan - Advanced Configure
If you are doing math and don't have a TI Programmable Calculator, you are at a disadvantage.