Hey, guys! I'm getting my 27" iMac late 2012 on Monday, and have already bought some extra RAM (crucial 8GB 1600MHz SODIMM for Mac). My question is if I can keep the original RAM and add the extra RAM? As far as I know, the iMac comes with 4 x 2 GB RAM, while my new RAM is one on 8 GB. How is it to mix different RAM brands and sizes? Here is the original link to the RAM I bought: http://www.netonnet.no/art/data/komponenter/internminne/sodimm-ddr3/crucial-8gbddr3sodimmformac/179811.7062/?ismobile=false And one more question: How is it to upgrade RAM before the first boot? Thanks in advance!