[personal profile] mjg59
Edit: Sigh, some further testing shows that it seems better, but not fixed. If you unplug the power while the CPU is over 80 degrees C, the machine will power off. I can't find any way of avoiding this - it seems to be handled at the embedded controller or SMM level, since as far as I can tell Linux isn't surviving long enough to even be aware that the event occurred.

Original entry:

The Asus UX21e (and maybe the UX31e?) has the irritating misfeature that it reloads the CPU thermal tables when you unplug the power. One consequence of this is that it'll automatically throttle itself much more aggressively on battery (reducing performance) but the more serious one is that the new critical power off temperature may then be lower than the temperature the CPU is currently operating at, resulting in the machine turning itself off. As far as I can tell from debugging, this is completely OS-independent - it still happens even if I stub out all the ACPI code for power supply events and there are reports of the same thing occurring on Windows. The good news is that it seems to be fixed in newer firmware versions. The even better news is that you can flash it without Windows. Just download the BIOS image from the Asus website, copy it onto a FAT formatted USB stick, insert that, go into the firmware (hit F2 on the splash screen) and start the flash program from there.

Good news

Date: 2012-05-20 05:51 pm (UTC)
From: (Anonymous)
We can find the BIOS update here : http://support.asus.com/download/download_item_mkt.aspx?model=UX21E I'm waiting the update for UX31E http://support.asus.com/download/download_item_mkt.aspx?model=UX31E


Date: 2012-05-20 06:50 pm (UTC)
From: (Anonymous)
Thanks for the tip!

Date: 2012-05-20 09:37 pm (UTC)
dreamatdrew: An orange leopard gecko half hiding behind the leaf of a 'lucky bamboo' plant, looking directly at you. (Default)
From: [personal profile] dreamatdrew
This... might not just be an ASUS thing. I have seen similar behavior on a certain HP in my possession.

Also, random, but why the hell would the thermal cutoff temp change based upon the power source? *BOGGLE*

Date: 2012-05-20 10:05 pm (UTC)
From: (Anonymous)
Maybe the assumption that while battery powered it may be on your lap rather then a desk, and not wanting to risk burning users. Heat == Power too thou.

Date: 2012-05-20 11:24 pm (UTC)
From: (Anonymous)
Bad assumption; I often use a plugged-in laptop in my lap.

Date: 2012-05-20 11:24 pm (UTC)
From: (Anonymous)
One possibility: you typically unplug a laptop before tossing it in a case and going somewhere.

FAT, but never NTFS

Date: 2012-05-22 04:22 am (UTC)
From: (Anonymous)
You should emphasize that this has to be FAT USB stick. Trying to use NTFS partition when flashing from BIOS can brick your laptop. This is what I did actually ;)

Same problems with Lenovo Thinkpad X120e I guess

Date: 2012-05-25 01:17 pm (UTC)
From: (Anonymous)

I think I'm having the same problems with Lenovo Thinkpad X120e. After some stress and CPU heat the system goes bonkers with thermal shutdown. Needs to cool down an hour perhaps before everything works again. Pretty lame stuff. I took some vids about this:

First, the thermal shutdown occuring in Windows:

Second, live Linux (SystemRescueCD) dying in udev activation phase:

Mr. Janne Paalijarvi

same on UX31e

Date: 2013-02-07 03:05 am (UTC)
From: (Anonymous)
I get a very sudden power cut out on my UX31e, either when it's been doing things for a while or when I yank the power plug out while it's running. I'll try the firmware upgrade too but yes it seems to be a problem on the ux31e as well. Thanks for posting this, it was very helpful.
From: (Anonymous)
I've upgraded to the latest BIOS (214) for my UX31E and it still powers off when unplugged and under a CPU load.
From: (Anonymous)
I also have a UX31E, and it has started to randomly shut off when on battery power. I recently installed the latest bios, 214, and it has not helped. I am running Ubuntu 12.04 LTS. I have tried all of this things found around this URL https://help.ubuntu.com/community/AsusZenbook

...but it still is acting up. Any help from anyone would be greatly appreciated.

Asus UX31e

Date: 2013-07-20 09:40 am (UTC)
From: (Anonymous)
Hey All,

The sudden power off when connecting the AC happened on my
ux31e when I had windows 7(out of the box), and still happens now with ubuntu 12.4 LTS. I also checked this issue(and some wifi connectivity stuff) with ubuntu 13.4 with no luck.

help risk of brick after bios update

Date: 2013-10-27 02:18 pm (UTC)
From: (Anonymous)
Hi everyone,

I suffered from many reboots ever since I upgradded to windows 8.1. I tried to flash Bios 214 by downloading it and running it in windows 8, files were in my "downloads" directory. It ran fine untill the 3rd step where it stuck at 99%, I couldn't move mouse cursor or anything, gave it 15 mins and finally turned it off...

Now of course the damn thing won't start again and get stuck after the Asus Spashscreen, then all I get is a blinking underscore on the first line of a black screen...

I can access Bios menu just fine by pressing F2 on Asus splashscreen. Now the trick is :
When I go to hte "start easy flash" menu it won't flash anything as he believes my 214 version is too old (since he belives he is running the 2144 version perfectly fine already.

What more can I do ?

I tried ibnserting my Wibndows 8 usb key to format everythibng but nothing happens at startup and I also belive this would not solve my whole BIOS situation right ?

potential fix - reconnecting battery

Date: 2014-01-30 07:16 pm (UTC)
From: (Anonymous)
I gave this a try: opening the laptop with a Torx T5 screwdriver and then pulling out the battery's connector (the black plastic part by the multicoloured cables) then reconnecting it. So far I haven't seen a crash since last night so it may have worked.

Re: potential fix - reconnecting battery

Date: 2014-04-12 07:32 am (UTC)
From: (Anonymous)
I tried many of the proposed fixes listed here and elsewhere for this fault on my (larger) UX31E. I had read about disconnecting the internal battery before but was reluctant, especially while my laptop was within it's warranty period. I got so fed up with failed attempts to fix this; bios & driver updates, power management settings, restores and clean installs, etc. that I mustered the courage.
I followed a tear-down guide and youtube video instructions (which included battery removal) and removed (for a few minutes) and reconnected the battery connection (that's the multi-coloured cable terminal connection (not a ribbon type) on the UX31E, which is best teased up from the board with a plastic tool). So far, I have not had this problem reoccur. I have even tested it after maxing out the CPU on a game to get the system nice and hot which seems to be one of the driving causes of this fault - i.e. a fail-safe shutdown of the CPU when changing power profiles. So, in my experience this solution does in fact resolve the fault - for now at least!

Potential Fix -Run Linux Mint !!

Date: 2014-02-06 08:27 am (UTC)
From: [personal profile] hakuin
I have a UX21E. I have done all the Asus software updates in Windows 7. I did the BIOS update to 214. The problem seemed to stop in windows, but it persisted in my linux systems -Crunchbang (built on Debian) and Archbang.
The problem is when running on battery power it shuts down sometime after it gets to about 65% or thereabouts.
However I have installed Linux Mint 16 (petra) (xfce desktop) and the problem doesn't seem to be happening with this distro.
So it might be worth trying a live usb and see if it's okay. Perhaps the problem will only be solved on a full HDD install though?

Anyway I'm pretty happy so far. Also Mint is real fast, and well built. I used to run Ubuntu but Mint has superceded them in the desktop distro stakes it seems.

power settings

Date: 2014-03-01 05:10 pm (UTC)
From: (Anonymous)
this seems to fixed it for me.

Go to your power options->change plan settings for the right one when you are on battery (mine is Balanced right now, e.g.)->change advanced power settings, look at EVERYTHING. Under processor management, my "system cooling policy" on battery is TURNED OFF by default, genius! That means when my laptop overheats on battery, it will turn itself off...

asus 21UX shut down on battery power

Date: 2014-05-12 07:34 am (UTC)
From: (Anonymous)
I tried most of the above fixes without success.

Finally, I simply cleaned the inside of the laptop (fan and air intake areas) with a vacuum cleaner. A small bit of dust apparently can push just above critical temp levels when on battery (as suggested by some of the comments above). I reset all power options to original settings, and the Asus is now working without fault.

Was the problem solved (UX21)

Date: 2015-01-05 01:43 pm (UTC)
From: [personal profile] ptulkens
I have a similar problem to what is described here: when disconnecting from main, the computer shuts off even though the battery is charged and working normally.

I saw a number of suggestions going from updating to BIOS 214 (I'm running BIOS 212) to fine tining the Power Management plan (setting the system cooling policy on "active" rather than "passive").

Have these suggestions been tested and what are the results ?

Re: Was the problem solved (UX21)

Date: 2015-01-13 06:13 pm (UTC)
From: (Anonymous)
Try to unplug the battery conector in the mainboard. I did it and the problem dissapear

Re: Was the problem solved (UX21)

Date: 2015-01-14 10:07 pm (UTC)
From: (Anonymous)
Thank you. Unfortunately, your answer cae after I eventually decide to send the computer for repair (out of warranty ...). I'll see if it works when it comes back but will keep your suggestion in case it does not or shows the same problem after some time (as it did after a first repair under warranty).

Best regards,

Unplug the battery

Date: 2015-01-13 06:12 pm (UTC)
From: (Anonymous)
I tried open the laptop, unplug the battery connector, wait 5 minutes and the issue dissapear. No more sudden shutdown below 50% battery...
(Win 8.1)

Re: Unplug the battery

Date: 2015-01-14 10:09 pm (UTC)
From: (Anonymous)
Good suggestion also. Is the 5 min wait time critical and why ?

My UX31E is doing the same

Date: 2015-03-04 02:19 am (UTC)
From: (Anonymous)
No luck also with my UX31E I tried everything that was suggested above (BIOS 214) and after some (good) time same problem. Running Opensuse 13.2, Ubuntu 14.10 and Windows 8 (looks like in Windows it's less frequent).
I was not very lucky with my power cable as during the last few years people sometimes have fallen over it!

I was wondering if it might be a problem in the power plug and was thinking of replacing it.
Any suggestions?


Matthew Garrett

About Matthew

Power management, mobile and firmware developer on Linux. Security developer at Nebula. Member of the Linux Foundation Technical Advisory Board. Ex-biologist. @mjg59 on Twitter. Content here should not be interpreted as the opinion of my employer.

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