Msi B360-F pro

Hey guys. I have the following issue.

I have built a new rig with 18 gpu MSI B360-F pro mobo, g4900 celeron 1151 processor, 8gb ram and 4 x 1000watt psu’s. All works well untill i add more than 10 gpus. Then the mobo boots into bios with message as attached. I have 4G encoding and mining mode enabled. I am running 5 rx 5500xt gpus and 13 x Vega 56 gpus. I have the exact same problem with another rig I built for a friend. He runs up to 12 cards…anything beyond 12 gives him the same error message.

Any help would be awesome and thanks in advance.