CUDA INSTALL FAILED

Why i cant install CUDA on my WIN 7ultimate 64bit SP1?
I have gpu GTX 550Ti

CUDA 9.0, 9.1 and 9.2 don’t support the GTX 550Ti

CUDA 8 is the last CUDA toolkit that will support that GPU.

Thanks for reply
Yeah i reinstalled windows but nothing has changed
I tried to install CUDA 8 but it did not work either

I have serious issue, My problem is that … I need cuda version 6.5 and i use this toolkit with visual studio 2010… At the same time, i have to use cuda 9.0 with visual studio 2015… Currently i have cuda v6.5, VS 2010 and VS 2015 installed… The problem is that when i install cuda 9.0 it start removing older version that is 6.5… please solve my problem… I need both 9.0 and 6.5 at same time

I am thinking to install cuda 9.0 in other path… what would u recommend…? Thanks in advance