Reducing T420s Power Consumption under KDE/Linux
If you own a Lenovo ThinkPad T420s (or any recent-generation notebook with a Sandy Bridge CPU) with Intel HD 3000 Graphics, this information may help you to reduce the power consumption under KDE/Linux:
Intel HD 3000 Power-Saving: Enable the following Kernel command-line options:
i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1
Force ASPM: Enable the
pcie_aspm=forceKernel command-line option
In KDE, go to “System Settings” “Desktop Effects” “Advanced” and set the “Scale method” to “Crisp”.
Overall, this brings my T420s’s power consumption down below 9 W. For best results, use a recent Linux 3.1-rc pre-release.