B-series(along with Q-series) mobo is targeted for business oriented system and has little difference in gaming features from H-series.
afaik the only notable difference between B and H series is intel Rapid Storage Tech which means B-series has native support for RAID (0,1,5,10 modes) while the H-series might need 3rd party controller for RAID. the other advantage is B-series usually has 4 slot of Ram Socket while H-series has only 2.
so if you dont really care about that feature H-81 or even better H-97 will sometimes be a cheaper option while not affecting gaming performance.
but to answer your question, Asrock B85M-ITX is enough for no-oc gaming rig(especially if you're building a small gaming PC)