MSI Z170A Gaming M7/5 How many GPUs?

So, I have 3 of these Boards. Two are M5 and one is M7.
With a PCIe 4x USB Hub on the main PCIe Slot I am currently running 9 Cards per Board.
I tried adding 10th card and it was recognized but the rig crashed. Since I had 4GB RAM on the board and I read another thread where missing RAM was addressed as the problem, I will try and put 16GB RAM on the Board to make sure it’s not the RAM.

I’m qurious, does anyone have a similar board and is running more than 9 cards?

I was actually hoping to get a total of 16 cards running on that board which in theory would work with 3 of those USB Hubs attaching 4 cards each and then there’s still 4 of the small 1x PCIe Slots left for the last 4 cards.