i am looking at ram upgrade options as i am about to dive in and purchase the 27" quad core imac. i know we need to install in pairs but do the 'pairs' need to match. can i leave the 2mb pair that comes with the computer AND add a pair of 4mb giving a total of 12mb? i read one site that said it was possible but would like some verification... does anyone know the answer? i did try to search these forums but didnt quite find what i was looking for.