This message was posted on behalf of Intel Corporation
john.kenny: Thank you very much for joining the Intel® Rapid Storage Technology communities.
In regard to your question, since the Windows® Server 2016 is not validated as fully compatible with the motherboard by ASrock, then, it is expected to have this kind of scenario. We recommend to use any of the operating systems that are fully compatible with the board:
At this point the best thing to do will be to get in contact directly with ASrcok to verify if they have further suggestions on this matter:
Any further questions, please let me know.