2 issues:
1) Windows can only support 8 of any type of card at one time (8 AMD + 8 nVidia possible)
2) That board can only support max of 8 cards, anyway. The 2nd M.2 is not connected to the PCIe bus. Only the SSD bus.
Thank you! So, I can save myself the hassle of installing EthOS? Like, 100% the second is only on SSD bus? It mentions in the manual an option to connect two PCIE devices to it.