I tried this on a Chelsio T6 100gbps card and a CX3 card. The T6 popped some on board regulators and the CX3 card would not post. I would be careful with these adapters. I would not use them on OCP 2.0 cards.
No luck with either OCP NIC in either mobo, never establishes a PCI-E LINK, tried changing a bunch of IIO settings but nothing seems to get it to establish a link. Also the main 16X slot is only establishing an 8X link with one of my CX4 cards.
I have a new theory about the powering up problem. I think the board isn't getting enough 5Vsb on this board with my current PSU. It has 2A on 5Vsb but at the ATX connector it's only 4V and slowly rising. I think the drop on the rail across the board is why the BMC isn't powering up.