utility to control the fan speed

 Lm-sensors is a hardware health monitoring package for Linux. It allows you
 to access information from temperature, voltage, and fan speed sensors. It
 works with most newer systems.
 .
 This package contains a daemon that calculates fan speeds from temperatures
 and sets the corresponding PWM outputs to the computed values. This is
 useful when this feature is not provided by the BIOS or ACPI, which should
 normally be the case on a laptop.