ERROR "the system is running in low-graphics mode" (with 7 GPUs)

Ubuntu 16.04.1LTS
AMDGPU-PRO Driver
radeon rx470 4gb x 7

Does not boot. Even system can not recognize 7 GPUs Can boot with 6GPUs no problem.
The BIOS can recognize with BIOS System Browser.

Anyone?

Anyone? 20 charactors

I solved this problem. I connect via ssh then system recognize for 7 GPUs. But still show up same error. Anyways, I don't really need a desktop so.