I know that this has been asked a lot, but I haven't anything that really answers my question. I'm going to be getting an iMac 27" when they come out and just get the stock 2x2GB sticks of RAM that come with it. I want to upgrade to 8GB... but I'm doing 2x4GB so that if I ever decided I wanted to do 16GB (I don't see why, but why not at least have half of it?). My question is, if I do this, should I leave the 2x2GB sticks in with the 2x4GB sticks? Or should I take them out? There seems to be some conflicting ideas about what RAM to use. I know you're supposed to do it in pairs, but I don't know how the iMac handles having 4 slots. My guess would be that it's best to use 2 or 4 sticks that are the same, I'm not sure about 1 or 3. But what about having 2 pairs that are different as noted above? Any insight would be helpful. Thanks!