400 MH/s for 10 1080 Ti's, 1 1080 and 1 1070 is not that impressive. 15 RX 570 4 GB cards will easily give you 420 MH/s ETH, 10.5 GH/s DCR dual mining and cost you less than half what those cards cost you.
it's about it running on the same board and its not an apples to apples comparison. You have 15 RX570 running on same board? or talking 3 seperate machines running 5?
Cryptomined got all 13 to work with Red Devil RX 580 8GB cards on smOS, 300 MH/s with stock settings and no Bios mod. I'm pretty sure you could add two PCI-E 1x to 3 extender cards to get 15 to work on the board, like Angry Chicken's RX 580 11 card 325 MH/s on the Asus Prime Z270-A video.
https://www.youtube.com/watch?v=beCjF9taFdU