I have this type of motherboard with 13 GPU running under Linux but I must have a faulty motherboard because some slot are not giving the best performance. If I swap cards or risers, it doesn't change anything, some slots are not performing very well. If I take a card and riser that is performing well on one slot and move it to a slow performing slot, my hash rate goes down while it was higher with the same card + riser on another slot.

I also have one of my slot that makes the whole rig unstable for some reason. If I use that slot, the rig crashes after a couple of hours while when I'm not using it I can mine a week without a crash.

I contacted Asrock and they suggest to return the motherboard. Have any of you had a similar experience?