Has anyone noticed that the 27 inch iMac (in my case the quad-core processor model) runs hot to the touch? I haven't had any performance issues, but man! The top of the monitor/chassis gets really hot!
I'm noticing it too. And I'm only noticing because I'm on day 2 and I'm starting to see the dreaded screen flicker. But yes, my i7 is super hot up at the top and I have to wonder if the heat is causing some of the video issue.
My previous generation one runs very hot especially near the top, but thought that this was just a way of using the external enclosure as a kind of full body heat sink. Unless you are having other issues, I wouldn't worry too much about it!