Ok, this happens when I install TensorFlow-GPU via the file> settings> project interpreter> + <add new library>. Now it redirects me to a link:
ImportError: Could not find 'cudart64_100.dll'. TensorFlow requires that this DLL be installed in a directory that is named in your %PATH% environment variable. Download and install CUDA 10.0 from this URL: https://developer.nvidia.com/cuda-90-download-archive
This error message is great. However, the cuda-90 archive does not, have a file 'cudart64_100.dll', although I did only check about 10-15 of the archives. So I went to the 10.1 version and it has curdart64_101.dll which is not helpful. Does anyone know a workaround as I am not a huge fan of colab.