Can I upgrade nvidia graphics processor?

Chips and boards are very different! The GPU soldered to your logic board and a direct feed to your CPU & PCH chips as you can see here, The Red outlined chip is the GPU, the Orange is the CPU and the Yellow is the PCH chip:

Here’s a listing of all of the systems within this series: MacBookPro9,1 All three had NVIDIA GeForce GT 650M GPU’s so there is no logic board upgrade possible,

A PCI board is a very different animal and you can’t alter your systems logic board to support it. What you can do is get an external PCI case to install a PCI GPU and connecting via Thunderbolt to your system. There was a company that made a external PCI box that would work using a feed through to an external display. You’ll need to look for a used one as the current crop of external GPU's are Thunderbolt 3 and won’t work with your system.