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 monitors temperatures, through available hardware monitor chips which expose their temperature sensors connected to different places inside your computer, and, according to your setup, does its best to keep those temperatures at your desired value. You can even change a fan speed according to the temperature of your hard disk. When choosing parameters for the minimum and maximum fan speed, try to set them by hand (disable all the VARIATE FANs checkboxes) and listen to the noise. When you hear no noise from the fan then you can set that value as the minimum fan speed for that fan. I suggest to use 100 as the maximum value, unless you hear so much noise from it. In such a case, you might reduce the maximum speed to 95 or 90. Obviously, nothing says that you can’t set 60 as your maximum value and, sometimes I myself set it that way. Consider that when the WARNING temperature is reached, the program sets the fan speed to 100, whichever maximum speed you set. One last word should be spent over the USE FAN x listbox. In my pc, when a fan runs faster, more than one temperature changes. You can say on which fan every temperature should rely. On my system, TEMP1 and TEMP3 are both influenced by FAN1.