Im not sure Maya has Pascal support, It didnt a month ago unless things have changed.
Its pretty well documented on the forums so maybe you shouldve done a quick search.
I got two Cubix Xpander that are attached to my Motherboard (ASUS X99A - 5960X and 64GB RAM). No matter what I do my system fails to boot with more than 5 GPUs. I got 1 x 1080 connected directly to PCIe in Motherboard. I also tried to connect just one Cubix and use the other PCIe Slot ...