Hardware Canucks tried the ASRock Z170M OC Formula mATX
A quote from the article:
ASRock's Z170M OC Formula may be one of the most powerful mATX motherboards ever created. Designed by famed overclocker Nick Shih, it has massive OC chops and yet still boasts gamer-friendly usability.ASRock Z170M OC Formula mATX Review @ Hardware Canucks