OK, now I have finished the script with speedstep feature and LCD backlight intensity control. ;-) Here is the script : http://bbns.idv.tw/debian/ac.sh It's written for ASUS laptop running acpid. Put it under /etc/acpi and chmod. Then, you have to create the file "ac" under /etc/acpi/events containing the following line: event=ac_adapter action=/etc/acpi/ac.sh execute /etc/init.d/acpid restart It will change to power saving mode after unplugging your ac power and change back if ac power resume again. Finally, add this script into crontab. In my case, I put it under /etc/cron.d and make it execute every minutes. It will change your CPU performance depending on your power resource. On my ASUS M2400E, without heavying calculation, the laptop can remain 3~4 hours before battery run out. Any suggestions or refinements are Welcome! :D Cheers Tim -- p.S. OK, now the only thing haven't done on this laptop is suspend and hibernate.