Greetings from Germany! I ordered an 27" 3.2GHz i5 with 8GB (2x 4GB) iMac from Apple. And I would like to upgrade the RAM of myself to 16GB. So, i want to by a single 8GB memory. -> http://www.crucial.com/eu/store/mpartspecs.aspx?mtbpoid=C8C45A3DA5CA7304 My question: can the iMac handles 3 used memory slots, or it is necessary that i have to buy a fourth one to "fill" all slots? I would be glad about helpfully answers!