RTX only works with cuda 10 toolkit. I use this pytorch conda enviroment and it works (both python3.5 and python 3.7):
conda=/usr/local/anaconda3/bin/conda
activate=/usr/local/anaconda3/bin/activate
deactivate=/usr/local/anaconda3/bin/deactivate

#python3.7
$conda create -y --no-default-packages --prefix /usr/local/pytorch/python3.7/cuda10.0_pytorch_1.0.0 python=3.7
source $activate  /usr/local/pytorch/python3.7/cuda10.0_pytorch_1.0.0
$conda install -y pytorch=1.0.0 torchvision cuda100 -c pytorch
source $deactivate

#python 3.5
$conda create -y --no-default-packages --prefix /usr/local/pytorch/python3.5/cuda10.0_pytorch_1.0.0 python=3.5
source $activate  /usr/local/pytorch/python3.5/cuda10.0_pytorch_1.0.0
$conda install -y pytorch=1.0.0 torchvision cuda100 -c pytorch
source $deactivate