This board going to have massive problems with hot cards! Dont forget, the hoter your gpu is the slower it works. So single Sapphiere RX 580 Nitro+ can do 32.5 Mhs with ETH at 70°C it becomes more memory errors and need to be restart or it hangs in windows same problem will be with linux. What happens if one of the this china capacitors are dead? You need to send it back and your miner stops making moneys... =( Sorry Octominer but its fail!
I prefer this mainboards
http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=886 and simple 008C Risers which I can change if they are dead it also cost less even with CPU and have 2-3 Years warranty.
Your asking for trouble mining at max like that with your cards personally I undervolt and save myself some heat and energy consumption.
Time will tell with these mobos but with high flow fans heat shouldn't be a problem as seen in the videos from octominer.com
The whole concept is to get away from risers which cause all sorts of issues particularly because of poor quality control in production