The P7H55 is ATX, it's a 4+1 phase pwm setup. meaning 4 phases for the cpu and one for the IMC. with a 4phase board stick to a quad core with no HT for ocing or quad core with HT with no ocing. any dual core with or without HT wont matter on that kind of board. The P7H55 is mATX, it's a 4+2 phase pwm setup. For being mATX is gonna have a bit less connections. is something you need to look into if you need those added connection options on the ATX board.