RAM upgrade for iMac 5k
Hello, I am in the process of ordering a new iMac 5k 27". i am going to get the upgraded processor 4.0Ghz and graphics Radeon 295x (4gb). I am thinking of upgrading the RAM at a later date and would like to know what the standard RAM modules are. Should I buy with 8Gb and replace later with 4x8Gb modules? or Should I buy with 16gb (2x8) and purchase another 2 modules (2x8) later? Do the RAM modules have to be the same brand etc? Can I buy the same modules in Australia? Thanks for any help
iMac with Retina 5K display, OS X Yosemite (10.10.3)