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 supports SCSI disks too. SpeedFan can even change the FSB on some hardware (but this should be considered a bonus feature). 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 (System Management Bus (trademark belonging to SMIF, Inc.), a subset of the I2C protocol) and works fine with Windows 9x, ME, NT, 2000, 2003, XP and Windows Vista. It works with Windows 64 bit too.

4.39 - added full support for Fintek F71889F, even at unusual addresses
- added support for a new method to access SMART data
- added support for SCSI and SAT hard disk SMART access
- added full support for SuperMicro PWS-865-PQ PSU
- added full support for Winbond W83795G
- added full support for SMSC EMC1402
- added SHORT and EXTENDED OFF-LINE SMART TEST in SMART tab. This feature works on a number of supported interfaces and not on all of them
- added voltage readings for Winbond W83793G
- properly read Tjmax on Core i7 based Xeons
- relabeled IT8512F to IT8512E