Monitoring PC Health: Power-Saving Modes, CPU Temperatures, Fan Speeds and Disk Usage

You finally decided to ditch Windows once-and-for-all, and took the leap into the exciting-but-scary world of Linux. And after reading tens of how-tos, you seemed to have found your footing in Linux and want to try new stuff. But hold on! Before you go around installing 7 different media players, 4 different browsers and switching between desktop environments just for kicks, you'd do well to install a few small applications which will ensure that you keep your computer fit and ready to take on anything you decide to throw at it. Monitoring your hardware is always an investment, but it keeps rewarding you for your proactive behavior day-after-day. This includes, but is not limited to keeping your hardware running at an optimum temperature, turning on power-saving modes on your computer and keeping your disks free of junk.

Over the next few paragraphs, you will learn a few valuable tricks to make the most of your current hardware setup.

Longer battery life while on-the-move, lower temperatures when not demanding full performance from your computer and prolonging the life of your hardware are just some of the advantages of using the power-saving modes available for your hardware. The "powernowd" service in Linux interacts with the cpufreq kernel driver to govern the processor power-saving mode. You will have heard of AMD's Cool n' Quiet or Intel's SpeedStep technology. You can customize the level of power-saving through the governors/preset modes which are available from the kernel:

Ondemand- This setting will use the upper and lower limits of your processor's clock speed and fluctuate between them as per your performance needs. So a simple card game will not push your processor beyond it's lowest clock-speed, ensuring that your hardware is using minimum power. Fire up a 3D game and watch the CPU frequency jump to its highest possible value, and use maximum power.

Conservative- This is just like Ondemand, but it's conservative at shifting up a higher gear during demanding loads.

Performance- Fastest speed and highest power consumption.

Powersave- Lowest speed and least power consumption.

On most modern distributions, the kernel has the CPUfreq driver built into it, so simply running the powernowd service is enough to turn on the power-saving mode. If your distro doesn't have powernowd installed (Ubuntu 8.10 does), refer to its documentation to know how to install the service and run it at boot-time. For people who build their own custom kernels, make sure to select cpufreq during kernel configuration and include it as a built-in driver rather than a module.