Today I worked on an 11 and 13" MBA, both both are max'd out spec's, 'ultimate' as we say. I had 9 web pages open, downloaded photo's from my camera to both machines, browsed the photo's with 'Just Looking' software, used VM Fusion with Win7 loaded on both machines used Microsoft Publisher, move some photo files in DropBox and also played back some 720p video clips ....the 11" is also currently plugged into a 27" ACD, the 13" is not... The 11" is silent, I haven't heard the fans yet. It's amazing. With all these programs open the only lag I notice is on the 27" ACD when scrolling for example, it's a little choppy. Now, when I close out of Win7 it handles everything, no lag, no fan noise and not too hot. The 13" on other hand roars doing the same tasks. I don't like that. From reading here I'm thinking it's normal for the 13" ... I could try a SMC/Pram reset I suppose. But I think it's just the way the machine is. I wonder why? Also, is there something I can do to "safely" control the fan speed without doing damage to the machine. I'm not so sure on the software recommended and under volting etc, I'd rather not do that. The fact the 11" is so quiet, even running windows is making it appealing over the 13" ... I hate fan noise.