I've recently upgraded the ram of my 21,5" late 2009 iMac to 12 GB (from the original 4 GB) using three 4 GB Crucial kits. I purchased the ram from their website using their software assistant to detect the correct model for my mac. I've been using it for a few months now and everything runs smoothly. I even removed the original Apple ram (although I have another free slot) to prevent any incompatibility issue. The problem is, I've noticed a huge delay when I put the mac in sleep mode and it started the exact day I upgraded the ram. It now takes 30-35 seconds to go to sleep compared to the 3-5 seconds it took before. I did a clean install when Yosemite came out but it didn't solve the problem. Do you have any idea how to fix this?