best stable CUDA & CUDNN for 840M on Windows 8?

I have search documents and know that 840M is compute compatible 5.0
It should be ok to run CUDA 9.0 + CUDNN 7.4.2 with python 3.5 or 3.6

But the CUDNN download page only have windows 7 or 10.
should I go ahead and use the windows 7 version?