SpeedFan is an application that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips.
Can access S.M.A.R.T. info and show hard disk temperatures, also has SCSI support.
Can access digital temperature sensors and can change fan speeds accordingly, thus reducing noise.
Supports Windows 9x, ME, NT, 2000, 2003, XP, Vista and Windows 7 (32 & 64bit)