I want to put 1 Asus ROG rx580 GPU and 2 Sapphir NITRO RX 590 GPU in my ROG STRIX Z370-H GAMING
 motherboard.
I have already the Assus ROG RX580 GPU.
Want to put another 2 GPU.
a) Can I put 3 GPU in Z370 H
b) Do I need to choose Asus ROG RX590 over Sapphir NITRO RX 590 as I already have asus rog 580