Has anyone successfully tried to upgrade the CPU in a 2011 21.5" iMac? Mine was shipped with an i5 2400s CPU. I was thinking of upgrading it to an i7 2600s (which is the processor that shipped with the build to order 2011 iMacs). However, after doing some research, I found out that the ivy bridge processors and sandy bridge processors use the same CPU socket. So, in theory, the 3770s should be compatible with the 2011 iMac logic board. The two processors are roughly the same price, so I think the 3770s is the way to go -- more performance for my money. It also uses about the same wattage as the 2400s and 2600s, so there should not be a power issue. I know there might be some drivers that might need updating. In the 10.7.4 update, OS X added support for ivy bridge processors and HD 4000 graphics. So, IF OS X can be run successfully after upgrading the CPU to the 3770s, I believe that as long as the computer is at least running 10.7.4 (which added support for ivy bridge processors) it should be fine. Since my iMac is currently running 10.8.3, all of the required drivers should be built into the OS. Oh -- and I am fully aware that this would void the warranty. The computer is over 1 year old now, and since I do not have AppleCare, there is no warranty anymore on it. If anyone out there has any suggestions for me, or any reason they believe I'm wrong, please let me know. I'll reply in the next few days after I make my decision on what I'm going to do. Any help is greatly appreciated.