Pls change the motherboard. I don´t know whats the others will say on it, but for me it´s a piece of junk if you want to use more than 5x vegas...
Asus mining expert is better.
I agree, go with Asus Prime Z270 A of P, i'm using both of them and they work fine with 8x RX 580 (you'll need 1 or 2 M.2 to PCIe cards).
Cheers