I just bought a Retina Macbook. I had to sell my 2010 Air to pay for my wedding, so the wife let me get this once we were married. I also bought a Sony PS3 monitor, and run the MBP in clamshell mode when I am home (the monitor is non-Retina, but still damn gorgeous looking...plus I use it for PS3 and XBox gaming when the wife wants to watch TV). But I digress from my own topic: Even closed running in Clamshell mode, I never hear the fan, and the computer is the coolest any of my computers have ever been in my lap during extended use. I even run Windows through Parallels, and both operating systems run smooth as butter with not a peep from the cooling fan. Apple's new cooling system is really something else. I've never had a Macbook run this smooth in my life.