Thanks for the debugging!
Since some methods are missing in your gist, you would have to help me out with some more debugging. 
It looks like the batch dimension is missing for x, but I’m not sure why and how your model seems to be working even without nn.DataParallel.
Usually your input should have the shape [batch_size, nb_features] to be a valid input for a linear layer.
If you are using a single sample, it should be [1, 65] for your model.
Since nn.DataParallel splits your data in dim0, you should provide a batch size being a multiple of the number of GPUs. In your setup you should provide a batch size of 3, 6, 9, ... so that the data can be split among each GPU.
Let me know, if you need some more help in debugging.