I'm helping my friend buy a 2011 27" iMac. Here's his question about RAM. Yes, he has $200-$400 to throw around, and he wants to max the sucker out to 16GB of RAM, partly for pride and partly because he may occasionally need that much RAM for some masters research simulations that he does, but mostly he wants 16GB of RAM for pride. With the four slots, does he have to look for a matched quad, or should he just get 2 sets of matched pairs? He's looking at the Crucial 1333 MHZ 8GB kit on Amazon and thinking about just purchasing two of them. Does the iMac ram run on dual channel or quad channel? Money's no object here, he just wants the best.