Discrepancy in Driver n Runtime API

I have installed latest Cuda toolkit 9.1, and using graphics card GeForce 8400 GS and Quadro M2000, in both the cases driver API is giving proper result however the Runtime API gives error—
“CUDA driver version is insufficient for CUDA runtime version”.
So I downgraded to Cuda6.5, I am using visual Studio 15(and I cannot use downgraded version), but with Cuda 6.5, there is no support for VS 15.
Then I tried installing NVidia driver as well, but old driver is incompatible with windows7.

Please guide what can be done, or what is the perfect combination of Cuda Toolkit + Windows + driver card + drivers.

There is no support for GeForce 8400 GS in any CUDA version beyond 6.5

I think the best suggestion is to remove that card from your system.

Which one to go then, we need GPU for image processing and computer vision, and need support for both desktop and laptop.
Also, what about Quadro M2000 ? Same issue happened with Quadro as well.