I wanted to let you know I found the problem based on your information regarding the Hardware and issues with the power cables or pci-e risers.

     Officially Asrock H110 Pro BTC+ can support 13 GPU's  What they aren't saying is. Due to a design limitation because of the increased PCI-e lanes that you have to run a mix of cards to make it work. They show you a build of 8 Nvidia and 5 AMD cards but claim you can run all AMD or all Nvidia with Linux stating the windows driver issue. What the tech guy told me after 4 hours of testing parts is " the board can only recognize up to 10 cards of any one GPU type so any time you run more than 10 Nvidia or 10 AMD you will begin to have initialization errors." I was told that's why they recommend 8 Nvidia because they have found that not all the boards can even work with 10 in a stable manor even though the design should support it. I have also noticed that once you add more than 8 GPU's I have to start backing down my overclocks.  So I have 2 of these rigs with one running 12 Nvidia and the other running 13 Nvidia. Both respond the same way. I go down to 10 GPU's and it works perfectly. Then I add the few AMD cards I have laying around and no issues.

   This is definitely not an issue on your software side, but something I feel you should know when this problem happens to someone else.