H110 with 13 gpus? How is that possible? H110 has 6 pci-e lanes, Z170 has 20 and it has trouble with 7 gpus...
At least 16 from the CPU + 6 = 22 lanes.
I'd bet that most of those 1x slots "share" with the 16X slot, though the M2 will eat a couple.
Could the 16x be hard-wired with 4 actual lanes (nothing new THERE).