Graphic card is not detecting in lspci after reboot, Ubuntu 18.04

I am using Nvidia graphic card 2080 Ti with Ubuntu 18.04.I installed graphic driver 450.66 via RUN file , It was working fine and i got display in both Motherboard HDMI and and Graphic card HDMI.

When i installed in a vehicle , now Motherboard HDMI is only taking and lspci is not detecting the nvidia graphic card. Graphic drivers are all ready there . but nvidia-smi says it failed because it coudnt communicate with nvidia-driver.

Same issue is happening many times . I am reinstalling drivers. but after some times, graphic card is not detecting.

Please provide a fix