The purpose of fans on your CPU is to blow off the heat that your processor may generate when a process is going through. A different method is set the maximum processor speed in the Energy options to 99% or lower so that TurboBoost is not used.Typically, CPU fan noises are heard when you reboot your PC (the whirring sound you may have heard upon startup) and it goes on to decline as the startup process completes. To adjust the CPU speed and to avoid TurboBoost (which makes the laptop overclock) you can use Throttlestop 8 or later to control this.It does not have the ability to undervolt. Intel XTU (Xtreme Tuning Utility) can lower the multiplier and monitor several functions such as temperature, TDP level, current cpu status and more.Nvidia inspector can however, lower the dedicated video chipset speed and memory usage without any visual effects. The change of the clockspeed there is unknown. In Optimus laptops however it may be smarter to run only on the integrated HD graphics chip. Nvidia Inspector has the ability to lower the graphical clock speed.However please be carefull about monitoring the temperatures. No need for an ACPI file, You can manually adjust the fan speed. Notebookfancontrol installs it’s on thermal control instead of the Intel ICH6 temperature monitoring and control.Todays laptops with Intel Core i3/i5/i7 chipsets need: Notebook Hardware Control with undervolting (beware of too low voltages which make the system instable and thus unreliable.RMClock (worked partially) as it does not have the ability to adjust the ACPI.Over the past few years I have seen the following things to optimize power/cooling and fan noise After a while more (unwanted) processes are running which turn the fan on.The aging of the laptop and thus drying out of cooling paste.Over the years Intel SpeedStep technology has become much better. After supplying an edited ACPI file you had the opportunity to change the CPU speed, voltage and videocard GPU Clock. In previous Intel Centrino notebooks you were able to use the program Notebook Hardware Control.

Notebook fan control