Use EWBF's CUDA Zcash miner here: https://bitcointalk.org/index.php?topic=1707546.0, I believe you can also use it for other Equihash coins but not sure.
Make sure you have the latest drivers, you may or may not have to also install the CUDA toolkit here: https://developer.nvidia.com/cuda-downloads, try it first should any problems occur before troubleshooting anything else.