I wouldn't hold my breath waiting for Asus to release a firmware update. Dual mining ETH + DCR a RX 570 will pull ~140 W between the GPU and riser and a RX 580 ~180 W. I have a 13 card mixed card build on a H110 Pro BTC+ dual mining ETH + DCR and it's been rock solid. Total power draw at the wall is 2475 W with a triple ATX PSU setup.
What mixed cards are you running?
Also what wall circuits are you running that into?
I have one 120v 20amp curcuit and one 120v 15amp circuit running to one room.