Phil did you test this board with 8 GPU's yet? Did you try with both AMD and Nvidia?
I've really been wanting to buy something like this : https://www.alibaba.com/product-detail/mining-machine-ETH-machine-4u-8xgpu_60708486305.html?
This is a bare-bones based on this motherboard, and would really speed up scaling/deployment for my new farm.
That is a slick case for the Onda B250.
In my GPU farm, we initially wanted to do a simple frame/case/chassis design like Genesis Mining but eventually adopted the open cage / open air approach to ensure best ventilation and easy maintenance, by just hanging GPUs with an S hook and zip tie to keep them in place -- all vents and blower pointed upwards.
My best observation is that ... if you are looking at 10, even up to 20, 30 rigs -- you might as rack them up, and have a controlled environment and use the casing/chassis and fans to redirect heat to create a hot air zone. From there use some form of a shroud/canvass to easily move air using blower fans (yunn6666 took this effective approach).
For my case, my group's long term plans in excess of 100 rigs (maybe 200 rigs if my 2018 cost analysis is approved by the group) and the open cage strategy was the simplest, fast-to-deploy and cost effective. All we had to do is have a cooling system for the entire warehouse. With Cryotonight and Equihash mining currently, we have successfully maintained the 32-33c overall temps for the farms.
I do have a crazy idea for the 2018 though - to standardize each rig 12 GPU at at time....
https://www.aliexpress.com/item/Crypto-Coin-Open-Air-Mining-Frame-Rig-Graphics-Case-ATX-Fit-6-8-GPU-Ethereum-ETH/32830718417.html?
Any takers?
FWIW, I'm also working on a frame and a case for the Onda B250 board.