Just 3 things:

- Install powertop and enable all suggested tweaks

- Depending on your kernel you should downclock your i915 graphics card and force pcie_aspm

- Later kernels (>3.6?) have a power regression which leads to higher consumption in Sandy Intel architectures

These are my energy tweaks for a 2008 MacBook, I don't have my x220 here, although they are machine independent:

echo 5 > /proc/sys/vm/laptop_mode echo 1500 > /proc/sys/vm/dirty_writeback_centisecs echo 0 > /proc/sys/kernel/nmi_watchdog

echo 1 > /sys/module/snd_hda_intel/parameters/power_save for i in /sys/bus//devices//power/control; do echo auto > $i; done for i in /sys/class/scsi_host//link_power_management_policy; do echo min_power > $i; done

for i in /sys/class/rfkill//soft; do echo 1 > $i; done

For the kernel parameters, a simple Google search should get you going.

What's the watt consumption you achieve? I must note I run Arch Linux with Xmonad and no desktop environment.

Ahahah. Ok, ok, yes, I'm running Unity on off-the-shelf Ubuntu. I bet you're getting much better battery performance than I am!

Well, running a lightweight desktop helps. I cannot say how much, though. Try monitoring wakeups using powertop while your machine is iddling. Anything above 30 or 40 is bad.