FWIW, after spending quite a bit of time trying to solve graphical issues I had, I found that there were quite a few issues/posts scattered around reporting crashes with intel /i915 that in hindisght seem closely related or even downright duplicates.
So far: issues # 4782, 7507, 7664, 7902, 7894. Forum post. Blog post (+ I remember reading another two but haven’t written down their urls).
The issue is that there’s tearing/glitches/artifacts/corruption with the fb driver when there’s no compositing (which i3wm doesn’t provide - probably explaining the high proportion of reports from i3wm users). People then switch to the intel driver because that’s the solution mentioned in posts to fix those glitches - but for some (yet to be found) reason intel is unstable for some people - from oopses to hard freeze/reboot.
In my case I’d get a few random reboots a day. I eventually made the connection and reverted to fb and so far haven’t encountered a single crash. In hindsight, given all the problems reported in this thread, I’m wondering which proportion is due to people using the intel driver instead of fb and being hit by bugs in intel…