The stock RAM in my iMac is in slots 1 and 3 and the open slots are 2 and 4... When you look at it in About This Mac More Info it shows up side by side. When you look at in System Information it has one listed as BANK 0/DIMM0 and the other as BANK 1/DIMM0. All of the screen shots people have posted here show the same step up... and when we install a pair of 8 GB SODIMM's in the open slots you end up with a 4GB stick and an 8 GB stick in BANK 0, and a 4GB stick and an 8 GB stick in BANK 1... everything I read says that RAM should be installed in matched pairs in the SAME BANK... SO SLOTS 1 and 2 are BANK 0 and 3 and 4 are BANK 1... What am I missing? Is interleaving that important? This is a new RAM expansion design for Apple and possibly for Foxconn, is it possible that they need to color code the slots like PC motherboards do?