Login stuck after reboot

I have the problem of logging in, I am stuck at the login interface.

I have tried to the solution provided here:

It is not related to my problem. I tried to “startx”, the last several lines show that:

Server terminaated with error (1). Closing log file.
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: server error

My GPU is GTX 1080 TI. I got this error after I separately reinstall the GPU driver and CUDA toolkit and reboot it. I install it on a server (DELL Precision T3600), but use it as a computer. The GPU is used for computation and X server. The system is Ubuntu 16.04. I have successfully installed them twice and it seems to be good for one or two weeks, but the above problem happened twice after computer is forcely turned off due to crash. This is the third time but the reboot is not forced. I attach the nvidia-bug-report.log and nvidia-installer.log.

I didn’t find the attach button. I copy the file below.

I have another question: since the power supply can not deliver enough power, can I connect the GPU to another power supply, and turn on the computer and GPU manully at the same time? Is it okay for GPU and the mainboard? I have tried to connect the new power supply to the computer, but the computer is not compatabile with the new pwoer supply.

If other information is required, please let me know. Thank you!

nvidia-bug-report.log (216 KB)
nvidia-installer.log (25.9 KB)

I attach the nvidia-bug-report.log as enclosure
nvidia-installer.log (25.9 KB)