Just FYI, for anyone who is looking to upgrade their CPU in their 2010 iMac, that it is possible to upgrade the CPU, as long as you use the same ones that were released in the iMac in the same generation. I just finished upgrading my CPU in my 21.5" iMac from a Core i3 550 3.2 GHz to a Core i5 680 3.6GHz. It took me about an hour and a half to get it all apart, and back together again. There are noticeable increases in GeekBench scores, with the i3 scoring 6510, and the i5 7683. Overall, the iMac runs a little hotter, but nothing out of the ordinary, and taking into account the i5 680 was originally a BTO option for the iMac in 2010, I figured it would work and took the leap. I also used an Intel ES i5 680 chip, for those who know what that is. It seems to work fine, with no problems in the iMac recognising the ES chip. It booted right up after I installed the CPU. I'm pretty satisfied with the upgrade, defintely worth it, with increased frame rates in some games, a noticeable increase in speed in Photoshop, and the turbo boost on the i5.