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.