There are 2 NVIDIA GPUs available in this machine. Largest GPU ID request for GPU #3 exceeds the number of available GPUs

I tried the example for the 3DShapeNet, however it came up with the following error:


```
There are 2 NVIDIA GPUs available in this machine. 
Largest GPU ID request for GPU #3 exceeds the number of available GPUs
FatalError at LIINE 8178. Program terminated.
```

I have two NVIDIA TITAN Xs available 