The motherboard chipset has pcie lanes as well. The B250 has 12 lanes.
In total, I am stuck with 14 NVIDIA GTX 1070 GPUs. It seems the recommended configuration by Asus is the only way to max this board. I am going to eventually try with AMD drivers and AMD GPUs if this hasn't been tested already. I want to see if there is a way to work around Asus's recommended GPU configuration.