Nope. I've run the ASRock H110 Pro BTC+ with 13 mixed RX 480/580 on ethOS and Windows with the latest AMD compute drivers and it's been rock solid for weeks. The one issue with this board is you need to file down the soldering on back of the x1 connectors on risers and cover them with two pieces of electrical so they don't short out, because the PCI-E slots are to close on the motherboard.
https://image.ibb.co/guB2aG/Screenshot_from_2017_11_25_20_33_56.pngYou have a riser plugged into the x16 slot with no problems? I have 12 GPU's currently running with electrical tape on the back of the x1 risers, skipping only the x16 slot on the mobo. When I try to plug the x1 riser into the x16 slot, I get a black screen on boot.....?