Since it included DirectCompute (which is an API inside of the DirectX 11 package). DX11 offers unified sound support, unified input support, unified networking support, and more that CUDA does not. But that's not what you were asking. CUDA and DirectCompute are virtually the same with one caveat: Microsoft will flex their industry muscles to get developers to use it and developers will want to use it because the same code will work on NVIDIA, AMD, and Intel GPUs. DirectCompute has everything to do with parallel computing. That is the reason why it was authored.