I'm always confused about how this works. I know that certain types of RAM work better if they are matched pairs. I have an iMac, Core2Duo, 21.5" that has the stock 4GB (2 x 2GB) in it. I was thinking of buying 8GB of RAM (2 x 4GB sticks) to take it to 12GB overall. Would this work since there'd be two sets of matching pairs or would I not be getting the full benefit of this RAM boost?