Never mind folks, I found that after restarting only then torch.cuda.is_available() returned True. One thing though that seems strange to me is that when updating the conda  environment pkgs pytorch & torchvision update to latest version 1.2 & 0.4 but cudatoolkit downgrades to 10.0 from 10.1, why is that, can’t we use cudatoolkit 10.1 instead of 10.0? Is there some conflict which forces conda to downgrade to cudatoolkit 10.0?