random laptop power outages with Ubuntu 16.04.1

[Jason Paul Joines]

       I'm running Ubuntu 16.04.1 with KDE neon User edition 5.8, having
recently switched from Kubuntu 14.04.5.  My hardware is:

Lenovo ThinkPad T510
latest BIOS, version 1.52
quad core i7 CPU, M 620  @ 2.67GHz
Intel integrated graphics using i915 module
8 GB SODIMM DDR3 Synchronous 1334 MHz RAM
500 GB Hitachi SATA drive
Intel 82577LM gigabit ethernet
Centrino Ultimate-N 6300 wireless

        Periodically, and with increasing frequency, the machine just
powers off.  The display goes black, with a small sliver of yellow or
orange flickering along the very left edge.  This lasts only a couple of
seconds and then the power cuts out completely.

        This problem did not start happening until about 10 days ago
which coincided with my switch from 14.04.5 to 16.04.1.  Power loss
seems to occur only during interactive use.  If I leave the machine
running all night, it is still running in the morning.  After a couple
of hours of use the problem occurs, and it seems to be getting more
frequent, beginning with once a day or so, then occurring three times
today within 5 hours of use.

        I think that I have been typing each time the machine has
powered off.  I typically have had Kate, Konsle, SeaMonkey, and
Thunderbird running.  Sometimes LibreOffice and VirtualBox too.

        The problem has happened while running on battery, with the
power plugged in, and running with the power plugged in and the battery
removed from the machine.

        It has happened using the built-in keyboard and when using an
external USB keyboard, with a external USB drive attached and without,
connected to the internet via wireless and via ethernet with wireless
disabled, as well as with and without KDE power management running.

        I have reviewed syslog, kern.log, and X.org.log around the time
of each power loss but can find nothing in common.

        Today, I ran the extensive Lenovo diagnostics at least twice,
including a memory test.  Everything passed.

        I am at a loss as to what is causing this problem.  Hardware,
kernel bug, power management, X or KDE, etc.  Any ideas or suggestions?


Jason
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