i didnt said you cant, i said its better. yes of course you can put the denomination you like, so that i hav bought an 2x4gib crucial to add my 2x2gib from apple, as I said in my post. who said that to me, that its better to have equal number of gib in all ports was a friend of my who make computers(i dont know the right word for this, english is not my main language), like a thechnichal man, who fix others people computers. he has a big store here in brazil. but if think its wrong ok. 😉