I have a mid-2011 iMac that originally came with 4G RAM which I recently replaced with 16G. It's the same brand/type of RAM as the original, each slot has the same amount of RAM (4G in each of the 4 slots). I have been able to start the computer with the new RAM. However, it seems that if I unplug the computer for any reason and then plug it back in, it will not start for two or three days. After a couple days, it starts and seems to work fine, except once my Finder application wouldn't start properly. Any ideas what the problem is?