I trying to run CUDA examples and always get CUDA error code=35 (cudaErrorInsufficientDriver) on Windows 7 Ultimate x64 with GTX 550 Ti.
Windows 7 Ultimate x64 (clean install)
Visual Studio 2017
Nvidia Driver 391.35
CUDA 10.0.130 411.31
Yes, you need to install CUDA 8, not CUDA 10. Your GPU is a Fermi GPU (old) and is no longer supported by current drivers and current CUDA toolkits. CUDA 8.0 is the last toolkit that supports Fermi GPUs.