System won’t boot with 3rd AMD card

I have an asus B250 mining mobo with a total of 11 cards. 8 nvidia and 3 amd.

When I plug in my 3rd amd card (6600xt) and power the system on, it gets as far as the screen where you can push Delete to enter bios and then completely locks up. I’ve tried swapping out risers, power cables, and order of the amd cards. Nothing will let the system boot.

Any ideas or advice would be appreciated.