risers work; but are definitely a hassle with wires and reliability.

this board looks promising because its from a reputable manufacturer;  but;  

1)   no mSATA or m.2 slot
2)   regular 2-slot spacing.  No bueno.  Needs to be 2.5 minimum when cramming more than 3-4 cards together.  the center gpu's will feel the pain.
3)   Need for 12V power to CPU port;  via a jumper wire from side connectors.  Just route the damned thing on the board.  Theres no extra features;  you have real-estate to work with; and layers.   USE THEM.
4)   6 pin PCIE;  8 pin is way better.  Plus many GPU use 8 pin.


Onda got it better for sure IMHO.   I wonder how thick the board is... how thick the main power traces are (the Onda boards are beefy power traces and thick boards;  seriously beefy).