Have you tried anything to narrow this down? No idea where to assign it.

Oh my god, finally someone with the same problem... I swear I've looked all over the web and nobody had this problem (and I've felt so lonely :().

The very same thing is happening to me on UX21E - it started around Feb 2014, I think.
The same scenario - it appears there is no specific trigger and the crash looks like complete poweroff with no logs at all - really nothing...

I've tried downgrading different packages over the past months and nothing really helped <cry>
I've even tried downgrading my whole system back to ~Dec 2013 (using ARM) - also didn't help (which is really weird).

I'm 100% sure it's not a hardware failure, as Windows is still rock solid.
Not a Gnome failure also, as I'm on KDE.

This issue is driving me crazy for months now... Please, tell me what and where to look for, which logs etc.
I will try to provide any required information to get this finally solved...

I wish I could tell you where to look. The only things I can think of that could cause a shutdown like this would be kernel related, so let's see if the kernel maintainers can help.

Could you try to reproduce this behavior on latest Ubuntu / latest Fedora as well? There were some similar reports about the UX31E freezing / shutting down related to the AC plug, so you should try that out and see, whether this is a Linux general problem, or not. Also, make sure your BIOS is updated to the latest version (BIOS 214).

My UX21E is on BIOS 214 since it was released (early 2013), and the corresponding issue started to happen on my Arch system around Feb 2014, as far as I remember.
I'm not really sure if it's a kernel fault, because I've tried to downgrade almost every package (including kernel), even several months behind, and it didn't solve those crashes.
Once it started to happen, I wasn't able to find any solution so far to fix it.
I'm also not sure about AC plug, as it's crashing on both AC and battery (it could be related to ACPI in general).

I will try to "reproduce" this bug on Ubuntu/Fedora latest bootable image in spare time.

I can confirm this didn't happen on Ubuntu 14.04 as I was running the development version from about December till March.

My bios is pretty old (207), so I'll upgrade it and see if that helps.

Lastly, I'll also try to reproduce on a Fedora bootable image.

EDIT : it also happened on the latest kernel image (3.14.4-1), I was idle and uploading stuff. Previous crashes had no particular internet activity happening, so I'd say it doesn't help in narrowing it down.

Ehh, no luck in narrowing it down here either...

All we know for now is it's BIOS independent - happens on both old and new versions.

I've done research on this subject and it seems to be a generic problem with many ASUS Zenbook ultrabooks. I've found people complaining about sporadic shutdowns on Windows 8 systems, too. Chances are high, this isn't a Linux-only problem, but more of a hardware issue. I would try to find a way to consistently reproduce this issue and get in contact with ASUS. Disabling VT-d in BIOS seems to partly fix this issue, so does disabling energy saving in BIOS. Avoiding hibernation / sleep seems to fix this issue completely. Shutdown your computer and never use sleep again (as hard as it sounds). Maybe fixing the DSDT / ACPI tables could fix this issue completely, but this is out of the scope of this bug report.

Good luck!

Thanks for your input ;))

The thing is, as I've said before, this is *not happening on Windows 8.1* for me - only my Arch installation is affected.
I'm using this device as my daily driver (most of the time connected to external screen) likely ~12h each day (developing, VMs etc. - so no, it's not idle ;)).
With this usage, Arch can crash 3-4 times a day, while Windows 8.1 is _ROCK solid_ - no single crash with 1+ year of usage.

Let me tell you the story of my UX21:
I've bought this ultrabook brand new in Feb 2013 (installed newest BIOS -> 214 and W8 + Arch combo).
Every single thing was fine (no single crash or even freeze!) on both systems till Feb 2014.
Then, my Arch installation started to randomally crash and nothing seems to help...

Yes, I've also seen those people fixing the crashes by removing battery, freeing up space on SSD, turning off powersavers/suspend etc.
But that's not the point.
If this is a hardware failure, then I demand a fix form Asus - I've paid for this hardware to actually use it :x

But there we go - Asus said that they don't support Arch Linux and so I'm on my own here...

Can't say I've experienced crashes under Windows either. No problems at all with suspend -- I don't use hibernate so I can't tell about that.

I did have problems under Ubuntu when the intel rc6 drivers came out ~ approx. two years ago. It stabilized in the end. Perhaps we could compare boot flags/parameters/setup for the Arch Linux kernel and most recent Ubuntu kernel.

My ux31a had the same symptoms (sudden shutdowns) for some time, but it happened about 1 time in a month.
It doesn't happen any more.
I'm not even sure if the reason is the same for you and me.

I never tested it under any other distributions or Windows.

That was long before this February, and was fixed for me for several months (or a year? or more? I don't remember).
I don't think that I experienced sudden shutdowns in this year.

Just googled this: http://technologicaltheologian.blogspot.ru/2012/10/zenbook-prime-and-unexpected-shutdown.html
It could be relevant.

> [Edit: It seems that disconnecting and reconnecting the battery has had some success for various Zenbook users. Note that this will void the warranty (which is nothing other than absurd, but be warned).]

This could be the solution that worked for me, because I disassembled my notebook to fix keyboard connector that came off.
I dunno.