[olug] Machine randomly powers off

[Ben Hollingsworth]

Hey all,

I'm seeing some weird problems with my desktop box (Ubuntu 16.04), and 
I'm not sure what to look for next.  It just randomly (as far as I can 
tell) powers off every so often.  It might stay up for a few days, or it 
might say up for a few minutes.  I've witnessed it a couple times when 
I'm using the console, but it usually happens when it's sitting idle.  
It always powers on & boots just fine when I press the power button.

There's no mention of anything in the OS logs.  The machine just dies cold.

MRTG graphs show nothing unusual related to heat, fan speeds, or 
voltages.  A visual inspection shows all fans spinning.

The UPS (which is plenty big & has a new-ish battery) doesn't hint of 
any problems.  The BIOS is set to power back on if it shuts down due to 
a power loss, but that doesn't happen, so I don't think it's related to 
external power.  I'm running a Seasonic 700W PS that's been working 
great for years.  I do still have my old desktop box from which I could 
swap the (smaller) PS, but I haven't tried that yet.

It has 4 sticks of RAM (2x4GB, 2x8GB), and I've swapped them out in all 
combinations, and swapped slots.  Memtest runs for hours with no errors, 
so I don't think it's RAM-related.

I also still have the mobo/CPU/RAM from my old desktop box (which is 
significantly slower), but those aren't individually interchangeable 
with the new system.  Swapping all 6 of my hard drives between systems 
is time consuming, so I'd like to diagnose further before doing that.

Before I go randomly replacing expensive or time consuming parts, where 
else should I be looking for the cause?  This is *really* annoying!

-- 
*Ben "Obi-Wan" Hollingsworth* obiwan at jedi.com <mailto:obiwan at jedi.com> 
www.Jedi.com <http://www.jedi.com>
The stuff of earth competes for the allegiance I owe only to the
Giver of all good things, so if I stand, let me stand on the
promise that You will pull me through. /-- Rich Mullins/