With some types of CPU it's possible to manually alter the clock speed while the system is running. This can be very useful with a notebook computer, for example, where you might choose to throttle-down the CPU speed when on battery power to save juice, or to minimize heat generation when the computer is resting on your lap.
The CPU Frequency Scaling Monitor applet takes care of this function but before it can be used some additional configuration is necessary.
Open a terminal window and type the following: $ sudo dpkg-reconfigure gnome-applets
You'll see a warning about how enabling the cpufreq-selector program could be a security risk if it is given root powers. This is true but, as always, usability must be balanced against security. The chances of a hacker exploiting this are very slim. Hit [Enter] and then, on the next screen, use the cursor keys to highlight Yes and hit [Enter] again.
Following this, right-click a blank spot on the top panel, click Add to panel, and then select CPU Frequency Scaling Applet from the list. A new applet will be added, showing the current speed of the CPU. By left-clicking on it, you'll be able to set either the speed you wish the CPU to run at, or the power-saving mode it should use (these modes very in name and nature from chip-to-chip but what they offer should be obvious from their names).
If your CPU has more than one core, such as Intel's CoreDuo series, each core must be configured separately. For example, a dual-core chip will need two CPU Frequency Scaling Monitor applets. Just right-click the panel as explained above to add another. To alter which particular core each applet controls, right-click an applet, select Preferences, and choose the CPU core under the Monitored CPU heading.
Note that each core can run at a different speed compared to the other core and be switched to a different power-saving mode.
To see the benefits or otherwise of scaling the CPU speed, see Tip 5, on page 65, which explains how to graph your computer's power con-
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sumption. You might also be interested in Tip 240, on page 282, which explains how to monitor CPU load.
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