Best bet, those cards stock can draw 140-150W without undervolting or even more. My RX 580 GB i have at 100W with undervolting running 30.5MH/s though.
Oh-My-God... ok. So one card on each line
30.5MH/s today? That's actually fantastic. I assume you mine ETH? I want to start with ZEC, because of the Ethereum news.