SpeedFan is a freeware program that monitors voltages, fan speeds and temperatures.

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 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 control 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. Several sensors, like Winbond's and the AS99127F support fan speed changing, as well as others from Maxim, Myson, Analog Devices, National Semiconductor and ITE, but the hardware manufacturer must have connected the relevant pins to some additional, yet trivial, circuitry. This means that if you have, say, a Winbond W83782D on a BP6 then you're ok, but not every motherboard with such an hardware monitor chip will be able to change fan speeds. From one of the very first hardware monitor chips that could be found in standard PCs, the National Semiconductor LM75 (and all of its clones, like the Philips NE1617 and the Philips NE1618 or the Maxim MAX1617) or the Analog Devices ADM1021, such chips have been greatly improved, both in their precision and in their capabilities. Current chips can monitor fan speeds, voltages and control fan speeds bu using PWMs (Pulse Width Modulation). Some chips can even be programmed to vary fan speeds without any additional software intervention. If your BIOS was programmed to setup such chips this way you can still try to use SpeedFan's Advanced Configuration to revert to manual (software controlled) mode. Winbond W83697HF, Analog Devices ADT7463, SMSC EMC6D102, ITE IT8712F, National LM85C and Maxim MAX6650 are very good candidates. Some SuperIO chips include temperature sensors too. SpeedFan can automatically detect them and use their features. The most used are National PC87366 and all of SMSC LPC SuperIO chips. SpeedFan can find almost any hardware monitor chip connected to the 2-wire SMBus (System Management Bus, a subset of the I2C BUS) Serial Interface and to the ISA BUS. SpeedFan works fine with Windows 9x, ME, NT, 2000, 2003 and Windows XP. SpeedFan can be minimized to the tray and is compatible with Motherboard Monitor 5.

SpeedFan can:

• handle almost any number of South Bridges
• handle almost any number of hardware monitor chips
• handle almost any number of temperature readings
• handle almost any number of voltage readings
• handle almost any number of fan speed readings
• handle almost any number of PWMs

What's New:

• added full support for ATK0110
• added Advanced Fan Control including a graphical UI for configuration
• DELL support is now working on 64 bit systems too
• DELL support can change fan speeds, but if the BIOS is overriding it, there is little SpeedFan can do
• added support for ST STTS3000 and ST STTS2002 DIMM temperature sensors
• reported temperatures and fan speed on Sony Vaio VGNFW21E
• fan speed is reported on some ASUS laptops with ATK0100 (like the F81Se and the K52JT)
• added preliminary identification of Fintek F71862
• PWM values can now be logged too
• temperatures are no longer tied to every fan speed as a default
• added F71809 PWM setting and reading
• improved SMART hard disk temperature reading if multiple attributes seem to report it
• rebuilt ARECA DLL with latest library and improved Areca RAID support
• more aggressive behaviour setting PWMs (this might help on systems where something else tries to change them)