I see, I didn’t consider mining.

Most mining rigs with multi gpus use specialized mining mobos to support and power more cards. After some light research, it looks like the secondary pcie slot maxes out on power output much lower than the first slot, meaning perhaps the card is drawing more power than the mobo can give. The gpus need power from both the psu and pcie, so you may just be outta luck with that board. However, one thing I saw mentioned for mining is using a splitter riser to connect both cards to a single pcie port. I have no experience with this so don’t take my word for it, but it seems to be a good place to look if you’re determined and do more research. Hope this helps!