It seems that with kernels 3.9 onwards there are some issues with fan speed and the 6730b model of HP notebook. I tried with Fedora 22 (my main distribution of choice), openSUSE Tumbleweed and Ubuntu 15.04.
The problem occurs only when the system is woken up after a sleep/suspend: fans spin at full speed indefinitely, without resort (apart from reboot/shutdown). This is a problem with ACPI. In order to solve this problem, if you’re using Fedora like me, create the file /etc/pm/sleep.d/99fancontrol.sh and fill it with the following:
case "$1" in
hibernate|suspend)
# Stopping is not required.
;;
thaw|resume)
# In background.
ls /sys/devices/virtual/thermal/cooling_device*/cur_state | while read A; do echo 1 > $A; echo 0 > $A; done
;;
*) exit $NA
;;
esac
and of, course, set it executable with chmod +x.
It basically flips on and off the current state of the cooling devices: with this script you won’t have the noisy fans at full speed on resume.