This article will explain how to install lm-sensors and associated applet to control the temperature of your PC (hard disk, cpu, etc. …).

The installation begins by installing lm-sensors:
# apt-get install lm-sensors

after that we proceed to the installation of the applet:
# apt-get install sensors-applet

After installation of the sensors-applet, software will ask some questions:
start on boot (yes/no)
I suggest to select yes

Interface to listen on:
127.0.0.1
Leave as is.

Port to listen on:
7634
Leave as is.

Once you have completed the installation of sensors-applet do configuration of sensors:
# sensors-detect

All questions will be asked, answer yes (it need look for the sensors).
At question:

To load everything that is needed, add this to /etc/modules:

#—-cut here—-
# Chip drivers
coretemp
#—-cut here—-

If you have some drivers built into your kernel, the list above will
contain too many modules. Skip the appropriate ones!

Do you want to add these lines automatically to /etc/modules? (yes/NO)
I suggest to answer YES.

We're done. Now on the top panel of gnome panel, select Add and from the list select Hardware sensors monitor.