Come on, don't tell me that you don't know than that is a typical mining Motherboard for back when PCIe 2.0 1x was good enough to feed data to a GPU. You fill it with PCIe 1x adapters with an USB cable wiring it to a separate 16x PCB adapter. And since to put that many GPUs you aren't going to do so in an standard case but most likely an open bench or custom case, being ATX Form Factor compatible isn't even a strict requeriment.