What is "artifacts"? Could you provide a very simple capx for this issue?
it is seen using your demo capx. it is like the fans don't like up fully, you see split second "holes" as in the fan is off by a few pixels, as it counts down.
using latest chrome using your demo .
rexrainbow here is a screenshot of the issue (using your demo, unmodified in any way):
Notice how the fans are not perfectly lined up (there is a break and you see the orange inbetween the fans)? This happens throughout the whole cooldown. At times, it is worse than others.