There are occasional screen distortions with nouveau and kernel 4.8.0-rc4+.
Have a look at the dmesg as well as the screenshots.

known bad: 9ca581b50dab6103183396852cc08e440fcda18e (see attached dmesg)
also bad: 593ee4edc51d99fadda9f6ee... (no dmesg available)
supposed to be good: v4.8.0-rc4 (as by the tag of 3eab887a55424...)

  The problem is hard to test for as the screen distortions only become visible
from time to time. Also, v4.8.0-rc4 has been tested with the plasma4 desktop
while 4.8.0-rc4+ versions have been tested with xfce4 so I can not tell with
100% certainty that the problem did not exist before.