The post time reveals everything. It must be a conspiracy. Team creates a coin, same team sets up pools, same team markets the coin, same team pushes the coin to an exchange (or exchanges). And then another cycle.
Did you flash the most recent BIOS. Can't remember the releasing date, but it's somewhere last month?
I am using the same motherboard and I had 9 bios-modded RX570 cards with mixed brands and models installed no problem in Windows10. I enabled mining mode, also set each GPU as "Gen2". Also, I set the internal GPU as the display output.