Last month, I announced the release of Athena on GitHub.
Athena is a C# word embedding program based on the original paper Efficient Estimation of Word Representations in Vector Space published by Tomas Mikolov in January 2013. It provides a full environment to manage a large text corpus and subsequently learn and query word embeddings.
This month, I have released an updated GPU accelerated version, which uses Cudafy.NET. This works with either CUDA or OpenCL devices and will auto-select depending on your hardware. A reference to Cudafy.NET is required, which can be downloaded from GitHub.
The GPU version provides between five and ten times acceleration over pure CPU depending on hardware setup. To the best of my knowledge, this is the only implementation of word2vec on a GPU using C# - please correct me if I'm wrong!
If you have already downloaded the CPU version, I strongly suggest you upgrade to the GPU accelerated version which is now available on GitHub: https://github.com/robosoup/Athena