[Intel-gfx] Video freezes continue to plague me

[Chris]

My system is a Dell Optiplex 780. I've filed several bug reports both
with the Intel Graphics Bugzilla and the Ubuntu Launchpad pages.
Initially back when this started in 2014 every 'freeze' would result in
an error of [drm:i915_hangcheck_elapsed [i915]] *ERROR* Hangcheck timer
elapsed... render ring idle' in syslog. It would happen every few days
or so and nothing that was done would correct the problem. Eventually in
2015 it got to where the video would still freeze however the
'Hangcheck' error would not show up in the syslog. Sometimes it got to
where I could go 30 or 40 days without a freeze and at other times 2 or
3 days it is totally random. I've tried different kernel versions, the
latest one I tried last year was 4.2.2 which still produced a freeze. At
that time I started going back to the latest Ubuntu 3.19 kernels. When a
freeze happens the mouse cursor will continue to move and all background
processes such as fetchmail, procmail, spamassassin, clamav and so forth
continue to work as if nothing has happened. Only the video is frozen.
The first thing that keys me to this is that the clock on the upper task
bar has stopped ticking over the seconds. Another issue that is
happening and has been for awhile is that the video will 'flicker' when
I'm switching between desktops or sometimes when I'm scrolling through
my twitter feed using Firefox. 

I've attached my Xorg.0.log in case it's any help. I'm using Ubuntu
14.04.4 LTS with Gnome 3.12.2.

-- 
Chris
KeyID 0xE372A7DA98E6705C
31.11°N 97.89°W (Elev. 1092 ft)
14:30:39 up 2:43, 1 user, load average: 0.17, 0.16, 0.27
Ubuntu 14.04.4 LTS, kernel 3.19.0-56-generic #62~14.04.1-Ubuntu SMP Fri
Mar 11 11:03:15 UTC 2016
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