I'm not sure if all B/H motherboards support higher memory frequency. ASRock has something like Non-Z OC but still their boards have tested memory up to 2800 only. Officially only Z170 supports higher memory, bclk etc.
ASRock was already making things that were "impossible" like mixing 2 different CPU sockets on one board or adding support to CPUs that shouldn't even run with some chipsets. There were many weird boards on the market so I bet they will figure out how to add additional features to their mobo series. Of course if there won't be problems with Intel as I doubt they're happy to hear what ASRock is doing.