[How To] Lenovo Thinkpad run in full speed with battery removed in linux

After using for nearly 9 years (since 2006) of my thinkpad X60 battery. It cannot be charged in a Saturday. As lenovo will limit the CPU speed when the notebook removed the battery. It decrease the performance a lot when battery removed. So for this case, I have searched for a solution.

Let's see my setup:
Lenovo Thinkpad X61 T8300 2.4GHz

How to override it:

When the battery was removed, Lenovo limit the CPU speed in bios, for this case, setting the  scaling_max_freq will not work.

#To see which frequency of the CPU you can set, you may:
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
2401000 2400000 2000000 1600000 1200000 800000

#So To override the BIOS limit:
echo 1 > /sys/module/processor/parameters/ignore_ppc

#replace the 2400000 for your max CPU speed
for x in /sys/devices/system/cpu/cpu[0-1]/cpufreq/;do
  echo 2400000 > $x/scaling_max_freq
done


Very nice and done.

Just a reminder that when override the bios limit may harm the mainboard. For this case, it is highly recommand to use i7z or phc-intel to lower the voltage of the processors (I have set it before that). It may have less chance for overloading the mainboard.

Cheers.

= = =
reference:
http://blog.patshead.com/2013/04/my-bios-is-limiting-my-cpu-clock-speed.html