anyone try 16gb in imac just wondering if the performance difference is worth it. It seems like it would be just $150 from owc to just max out ram to 16gb if I gave the 4gb original as a rebate. Does the 12gb ram slow it down even if they are not matched pairs (2x2 or 4x2). just curious it sounds like some people have problems running 12gb maybe stay with 8gb or just go for the 16gb. let me know what you guys think.