Error message adding more than 4 cards on Asus Z390P

Whenever I try to add more than 4 GPUs I get this error message. I’ve swapped out all the risers and psu. I’ve even replaced the motherboard and keep getting the same error. I have above 4g enabled and gen 2 on all the pci settings. Any help would be greatly appreciated.

I am having the same problem with the same motherboard, after looking into it, it seems it is just the motherboard.

Really? Damn. I thought this motherboard was made for mining

Did you manage to solve this problem because I have the same?

Nope. I know people using the same board that have 5+ cards on it too so… idk. I have 2 rigs with 4 cards each now, luckily had an old pc was able to scalp for parts, only had to buy an old motherboard.

Enable uefi mode , cheers