Hello all, I have a 2011 27" iMac with the stock ram (two 2gb for a total of 4gb) and I want to install more ram. I am a noobie at this stuff and am overwhelmed by the info I find when googling the proper way to do this. I have this ram is it the correct ram to use? And is it ok to mix with the stock ram already in the iMac? Thanks in advance.