Not able to overclock 6 GPU on Ububtu

Hi,

This is my environment:

OS: Ubuntu 16.04
6x GPU ASUS DUAL GTX 1070
Nvidia driver 387.34

I need some help to get overclock each GPU. I can only overclock the GPU0, but when I try to use this command:

nidia-xconfig -a --allow-empty-initial-configuration --cool-bits=28

After restart, linux hangs and this message appear: The system is running in low-graphics mode”. I can enable the system again copying a backup of my file xorg.conf.

I have connected the monitor in the main board.

Does anyone send me the correct xorg.conf or help me?

I can execute the nvidia-settings, but only GPU0 is available to be overclocked.

Thanks and happy new year!

https://devtalk.nvidia.com/default/topic/1024139/?comment=5212213