Unfortunately, CPU frequency scaling can
currently only be monitored on Linux machines that have support in the
kernel. It can however, support the several generations of frequency
scaling interfaces in the kernel.
When there is no CPU frequency scaling support in the system, the
CPU Frequency Scaling Monitor only displays the current CPU frequency.
Right-click on your top or bottom bar, or wherever you want the applet to be you should see the following screen
Now you need to Click “add to panel”Once it opens you should see similar to the following screen
Now you need to find the “CPU Frequency Scaling Monitor” and click on add or drag this onto your bar.
Once it added in to your bar you should see similar to the following icon
Open up a terminal and enter the following command
sudo dpkg-reconfigure gnome-applets
Now you should see similar to the follwoing screen select ok and press enter
Next one is Install cpufreq-selector with SUID root select yes and press enter
Press enter again and you’ll be back at the terminal window.
Left-click on your monitor and you should be able to choose the speed of your processor