I appreciate the language barrier, but full sentances are always an aid in helping readers understand the problem
Are you saying that you have a 6600gt and that you have managed to get to 550/1050, but you want to get it to a higher overclock and therefore are asking if you should change the motherboard to do so?
My answer to that would be 'no'. Overclocking is not guarenteed and it's quite normal that you should not be able to reach 1100 on the memory - the motherboard will not be holding you back significantly. Instead it's likely to be the limitations of your graphics card.