As I'm apparently not allowed to write at the correct place (and although it will probably ignored here):
The OpenCL FP16 support for Vega on Windows 10 (1703) seems to be broken, or missing important features, with all Vega drivers so far. Depending on what you are trying, the GPU, or the whole system crashes/hangs.
The best way to reproduce crashes is using SiSoftware Sandra 2017 running the GP (GPU) Image Processing, or Scientific Analysis, benchmarks in Half-Precision.
Also the AIDA64 GPU SHA-1 benchmark is producing errors on Vega 64, but I'm not sure if this is related to the same issue right now.
Sorry for this late reply and thanks for reporting it.
It would be helpful if you could share some more details about the issue (for example, any feature/operation seems to be broken or missing) and provide a reproducible test-case manifesting the problem.