Cuda Toolkit 9.1 on Windows 7 x64_installation failed


I really want to know how to fix the problem on my laptop of installing cuda_9.1.85_windows.exe on a Windows 7_x64 system. After choosing the insallation derectory an error window comes with “Non 7z archive” with the title “cuda setup package:error”. I try to update the driver of my NVIDIA GeForce GT 720M but it seems doesn’t work. Can anybody help me to solve this problem?

Thanks a lot!

GT 720 M is a Fermi GPU (compute capability 2.x) which is not supported by CUDA 9.0 or 9.1