Unable to install nvidia driver on ubuntu 16.04

I have done every possible options available in linux forum but nvidia drivers for gtx 1650 super (nvidia 440) is not installing in my board. I am using intel serverboard s2600stbr with xeon silver 4210 processor. I have tried adding graphics ppa from terminal. Updated it. while calling the 440 driver it is showing package not found. Downloaded run files from nvidia website, that also showing please close x server. Please tell me how to fix this problem, step by step.need your help guys.