@ben.bowles, I am experiencing the same. I, too, have a GTX 1070 with a previously installed version of hand-compiled TF and cuDNN5.0
What above error means is that the version of TF you are installing expects cuDNN 5.0, while you have cuDNN 5.1 installed.
I am a little confused about the instructions provided by @jeremy in this thread: The Anaconda3 wheel installs python 3.6, while the pip install tensorflow-gpu installs a version with something something 3.5 in it - python 3.5?
Anyways, I solved it by downgrading to cuDNN 5.0. I have no idea what adverse effects this might have, but at least it runs.
I somehow hypothesize that in my case the confusion might be caused by pip/conda’s inability to cleanly uninstall my old TF installation, since it was hand-compiled (true??). I don’t know if this is true or how to remove cleanly.
Anyways, my workaround appears to work fine, if with a bad feeling about potential version mismatch.