besides the fact that Win10 installed the update even though auto updates were disabled and with the tons of the usual problems, there is one major one, which still remained after a clean reinstallation.
I with this Win10 version I can use just one GPU. It does not matter if I use 2,3 or 4 GPUs and in whatever (nonsense) viarity I set them up, the problem is always the same. When I open the device manager there is the little warning sign visible on each but the 1. GPU, when I click on either of GPU 2-4 it says the reason this card cannot be used is CODE 12 = Bios/Uefi doesn't support the card with enough power. Well I tried the possible solutions for this problem, but unsurprisingly they did NOT work, 'cause as I guessed from the very start onward this problem is caused by Windows 10 Fall Creators Update.
So now I am either forced to reset / reinstall it to a previous version or wait some days and hope for a hotfix update.
Oh and btw it does not matter which driver version you use.
In case you ask: No not any of my devices has any kind of dmg, everything works perfectly fine!