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.

I was running it off of a dual 120V 2400W PSU I ordered from a manufacturer on Alibaba and a 1000 W ATX for the motherboard and risers. The dual 120V 2400 W PSU has 18 PCI-E 6+2 connectors that I use for the GPU VGA power inputs. Total cost through PayPal was $181 and shipping via DHL direct from the manufacturer was very quick.

http://www.panto-tech.com/products/206-110v-260v-power-supply-2400W-for-miner.html

For a while it ran quiet at less than 50% of the capacity. When you run it at more than that, the fans got progressively louder the more wattage you pull from it. Recently the fans started running louder and it became annoying to deal with the constant high pitched whining sound. I got tired of dealing with the noise and switched to a triple ATX PSU setup with a triple ATX power adapter cable.

https://www.aliexpress.com/item/New-24-Pin-20-4Pin-Triple-PSU-ATX-Power-Supply-Adapter-Cable-18AWG-Wire-For-Mining/32827769189.html?

The same manufacturer also has the same PSU with only the 18 PCI-E connectors and it's about $30 less, so I think that may be a better option for a dual PSU setup since I don't use the ATX 24-pin or sata/molex connectors on it.

http://www.panto-tech.com/products/207-110v-220v-power-supply-2400W-for-miner.html

This is the same PSU BBT used in his 21 card build on the Asus B250 mining expert live stream and you can hear how loud it is.

https://www.youtube.com/watch?v=miUoqnUqk9M&feature=youtu.be&t=6201