For anyone wondering about the PCIe slots on this motherboard, have you tried using a newer processor which supports more PCIe lanes if you have reached a limit? I have found a limit of 14 GTX 1070's with an INTEL I5-7500. Curious if upgrading to a new CPU would help?

I've also noticed how this motherboard will not boot at all (also with a black screen) if there are more than 14 GPUs connected to the PCIe slots.