18.04 - GeForce GTX 970 doesn't work with NVIDIA driver v450 at all

Hi, for my Ubuntu 18.02 the recommended NVIDIA driver v450 doesn’t work. I only can use outdated driver v390. I added bug reports regarding the working v390 and nonworking v450.
With Ubuntu 20.04 also the v390 is not working :-(

Can you give me a hint what’s going wrong!?

Regards, D. Ahlemeyer