How to Upgrade the Memory in the 21.5" iMac (Late 2012)
http://www.youtube.com/watch?v=D8Tuq373wPs
By OWC
http://www.youtube.com/watch?v=D8Tuq373wPs
By OWC
Orderd mine with 16GB. The risk, the time, the skill and the cost of all the tools make it not worh the hassle of upgrading the ram youself to save some 50 bucks or so.
Actually closer to $150 if you already have the tools and get the memory yourself. I've seen 16gb (2x8) 12800 SO-DIMMs going for as low as $50.
Others say you can swap out the RAM without having to remove anything other than the HD and Fan. The bigger issue is possibly voiding the warranty by breaking the adhesive seal and then re-sealing it.
I've determined that 8gb is fine for what I'm using the iMac for, however sure would like to swap out the horribly slow 2.5" drive for a SSD.
In the past Apple has not voided warranty of customer opened machines. Now if they determine a problem is the result of faulty hardware repair/upgrade not by an ACS provider then yes they will deny coverage of effected components. I.e. if your hard drive fails and they suspect you have opened the machine up for whatever reason at some point, they are most likely going to replace the drive with no complaints.
Of course accidentally breaking the glass is a guaranteed out of pocket repair...