I don't think there would be a problem, as mentioned earlier, if OWC is selling it would almost certainly work. My only question to you is, what on Earth are you doing with your iMac that 16GB isn't enough? Heck I "only" have 12GB and have zero page outs, even running multiple apps as well as running Windows 7 under Parallels. I still have plenty of memory left. So, I'm just curious what you are using your iMac for that 16GB doesn't cut it? Obviously some people do need 32GB or else OWN wouldn't sell it, but I'm just curious.