Hi, I own a 900x3c with BIOS P04AAC and am also experiencing acpi issues. Is this the latest bios? Also I see the function keys for keyboard backlight control is supposed to be working in Ubuntu 12.10 (see here), however they don't work me. Still, the backlight do seem to turn on when it gets a bit darker.
Also I've been checking PowerTOP for stuff taker more power than its supposed too.. First of all the audio intel codec has a bug, which is easily fixed by adding this to your /etc/rc.local (as explained in the link):
However I noticed something else with wireless in PowerTOP. I have something called "radio:samsung-wlan" (using about 1.5W) and then "Network interface: wlan0 (iwlwifi)" (using about 200mW). Both are listed as "Device". I'm wondering if the samsung-wlan (running at 100%) is something I really need for wireless, or if it's just some sort of duplicate of the other (Network inter..). It just seems strange to have to two of these running at the same time.
echo 1 | tee /sys/module/snd_hda_intel/parameters/power_save
echo Y | tee /sys/module/snd_hda_intel/parameters/power_save_controller