No GUI after install the Nvidia tesla V100

OS:Redhat 6.7
Card:Tesla V100*2

I install the drivers for the V100,It seems successful.But I lost the GUI of that server.
for nvidia-smi,I got
±----------------------------------------------------------------------------+
| NVIDIA-SMI 390.46 Driver Version: 390.46 |
|-------------------------------±---------------------±---------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
|===============================+======================+======================|
| 0 Tesla V100-PCIE… Off | 00000000:AF:00.0 Off | 0 |
| N/A 41C P0 26W / 250W | 11MiB / 16160MiB | 0% Default |
±------------------------------±---------------------±---------------------+
| 1 Tesla V100-PCIE… Off | 00000000:D8:00.0 Off | 0 |
| N/A 40C P0 24W / 250W | 11MiB / 16160MiB | 0% Default |
±------------------------------±---------------------±---------------------+
In fact I could run the cuda9.0 demo successful.
However,after restart the machine,I can’t get into the gnome desktop.
The only thing I saw in the screen is blackscreen,and I could login the cmd with alt+F2.
what’s more,everything in VNC is also black.
but I could get GUI of specific program from Xshell.
I try everything I could do.
I use nvidia-xconfig to generated the/etc/X11/xorg.conf and reboot,nothing changes.
If I run nvidia-setting,there is three errors.

ERROR: Error querying enabled displays on GPU 0 (Missing Extension).
ERROR: Error querying connected displays on GPU 0 (Missing Extension).
ERROR: nvidia-settings could not find the registry key file. This file should have been installed along with this driver at
/usr/share/nvidia/nvidia-application-profiles-key-documentation. The application profiles will continue to work, but values cannot be prepopulated or validated, and will
not be listed in the help text. Please see the README for possible values and descriptions.

You do not appear to be using the NVIDIA X driver. Please edit your X configuration file (just run nvidia-xconfig as root), and restart the X server.

If I try to run startx,the respond is “No screens found”

Please run nvidia-bug-report.sh as root and attach the resulting tar.gz file to your post. Hovering the mouse over an existing post will reveal a paperclip icon.