different feature and price .. the asrock is good
vview commparison fetaure : http://us.hardware.info/comparisontable/products/185773-186214-186264-186514-186524-186526-186527-186528-186529-186545-186557-186770-186793-186816-186835-186838-186839-186853-186854-186855-186901-186917-186919-186920-186935-186948-186949-186950-187095-187097-187665-187675-187678
yes good . the Extreme4 uses a 12 phase power design(Digi VRM) and gigabyte D3H is the 8-phase CPU VRM
and if the mobo had bigger VRM will get more pottensial OC .. just@suggestion