I recently started witnessing small graphics glitches with my Ubuntu 14.04 installation which has been running fine for a while with no graphics issues. The glitches usually happen at most bottom area of the screen, but sometimes work their way up. These are intermittent flashes (lasting for only half a second or so) of black lines that happen every few minutes, depending on what I am doing.
At first I thought perhaps a bad cable, but I noticed that while playing movies in Ubuntu the problem does not happen, nor does it happen on other modes of my TV (like using my PlayStation) so I know it is not the TV set.
While I am not able to reproduce any behavior accurately that would trigger the glitches consistently, what I did notice was that the glitches were often correlated to certain mouse behavior (either scrolling in a web browser, or navigating menus and clicking on files in Unity. That being said the glitches have occurred when there is no input activity.
I tried to record the glitches with Record My Desktop but the glitches would not happen while that program was running, which leads me to think it is something related to either Compiz, Unity or something with the mouse.
Thinking that it might be related to Compiz, I tried
compiz --replace with no luck. Restarting the machine hasn't changed the behavior. The only thing I can think of that changed was a system upgrade. Also, i logged into Gnome instead of Ubuntu regular and got the same glitches.
I also tried completely resetting the video with:
sudo apt-get install --reinstall xserver-xorg-video-intel libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core sudo dpkg-reconfigure xserver-xorg sudo update-alternatives --remove gl_conf /usr/lib/nvidia-current/ld.so.conf unity-tweak-tool --reset-unity
with no success.
Seeing now that even resetting the video configuration is not working, I am wondering what else there is to try to resolve this issue.
Running Ubuntu 64 bit on an Intel NUC 5i7RYH which has Intel Iris Graphics 6100 processor.