Installation help for NVIDIA GTX960 with Ubuntu 20.04

Hi, I am having trouble installing the proper NVIDIA driver with Ubuntu 20.04 for my NVIDIA GTX 960. The default driver in both ubuntu PPA and in NVIDIA site shows the 440 for NVIDIA GTX 960. But the installation fails with the error

I am able to install driver version 390. But then I don’t get proper Cuda version to install along with that on ubuntu 20.04

I need some help with this as I have spent quite some time on this.

ERROR: Unable to load the kernel module ‘nvidia.ko’. This happens most frequently when this kernel module was built against the wrong or improperly configured kernel sources, with a version of gcc that differs from the one used to build the target kernel, or if another driver, such as nouveau, is present and prevents the NVIDIA kernel module from obtaining ownership of the NVIDIA GPU(s), or no NVIDIA GPU installed in this system is supported by this NVIDIA Linux graphics driver release.

Please see the log entries ‘Kernel module load error’ and ‘Kernel messages’ at the end of the file ‘/var/log/nvidia-installer.log’ for more information.
-> Kernel module load error: No such device
-> Kernel messages:
[ 1540.442908] nvidia-nvlink: Nvlink Core is being initialized, major device number 237
[ 1540.443248] nvidia 0000:08:00.0: vgaarb: changed VGA decodes: olddecodes=none,decodes=none:owns=none
[ 1540.443269] NVRM: The NVIDIA GPU 0000:08:00.0 (PCI ID: 10de:1401)
NVRM: installed in this system is not supported by the
NVRM: NVIDIA 440.64 driver release.
NVRM: Please see ‘Appendix A - Supported NVIDIA GPU Products’
NVRM: in this release’s README, available on the operating system
NVRM: specific graphics driver download page at www.nvidia.com.

I am also looking for some help. I hope it will be solved asap by any team member or expert