Welcome to SpeedFan

SpeedFan is a freeware program that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. info for those hard disks that support this feature and show hard disk temperatures too, if supported. SpeedFan supports SCSI disks too. SpeedFan can even change the FSB on some hardware (but this should be considered a bonus feature). At the lowest level, SpeedFan is an hardware monitor software that can access temperature sensors, but its main feature is that it can change fan speeds (depending on the capabilities of your sensor chip and your hardware) according to the temperatures inside your pc, thus reducing noise and power consumption.

SpeedFan works fine with Win9x, WinME, WinNT, Win2k and WinXP.
SpeedFan can be minimized to the tray and does its best to be compatible with other hardware monitoring softwares.

Warning:

Please note that SpeedFan is an extremely powerful tool. When first installed, it is configured only as an hardware monitoring tool. This means it won't try to change the speed of your fans. Changing the FSB is the other operation that should be done with care. Anyway: changing the FSB should cause no harm to your system but an hang up :-) Anyway: this is an advanced option too and you should try it only if you know what you're doing.

My position on CPU cooling and fan speed changing

How to configure SpeedFan

What if SpeedFan hangs while scanning the SMBus?