You can't revert windows 8.1 back to windows 8 or windows 7 without a fresh install. Also, this is a fresh install of windows 8.1 - I got the full install from my Technet subscription.


But to happen on 3 computers? With different hardware and different GPUs?

It definitely seems to be windows 8.1 itself but I'd like to try to help pinpoint what causes the problem so we can find a solution.