How to train on GPU 1, while leaving GPU 0?

Mine 1st GPU is Old Quadro, doesn’t support new PyTorch Version. Another one is new Tesla K40.
Just wants to start on GPU 1, instead 0.
I can’t remove old one as Tesla don’t have display port.

So how to train on only GPU 1, while leaving GPU 0 ?

Duplicate of https://github.com/OpenNMT/OpenNMT-py/issues/1707