I recently got a new iMac (3.6 i5, 21.5") and want to upgrade the RAM myself. I would like to get it up to 16 GB, but the cost of me getting that laa at once is a bit prohibitive. Is it possible for me to get an OWC 8 GB kit now and then add two more 4 GB sticks at a later time, or do they have to be matched or paired in some way? Also, the iMac shipped with 4 GB of ram (on 2x2 GB sticks I am assuming). If I got an 8 GB kit, would it be possible for me to just add the 2x4 GB sticks and have 12 GB of RAM while I wait for more $ to get the rest of the 16 GB? Thanks in advance.