Anyone using the MSI Z170-A Pro for more than 4 GPUs?

I've got mine set to Gen 1 and >4GB in the BIOS.  All the cards show up fine and Claymore recognizes all of them, but when Claymore starts and gets to Create GPU Buffer on the last card (GPU0), the system hangs.

I'm on Win10 Anniversary with latest Nvidia drivers.  I've got 4GB RAM installed and virtual memory set to 16GB (16384MB). These are all EVGA GTX 1060 SC 3GB Cards.

Any ideas?