I have a 2012 13" MBA high-end version with 8GB RAM, and OS X ML is installed. When I'm using it on battery power, it's absolutely silent, and this is when I'm at the most active. However, when I get home and plug the MagSafe in, after some time, the fan kicks in, and this is when I'm doing nothing. At least, for today, I have System Preferences, Notes, Chrome, Evernote and Parallels open, and on Parallels, I have a browser and a word processing app open. No videos or audio is playing as well. What's even more surprising is that when the screen saver is running, the fan just kicks into full gear. I set my screen saver to "Shell." As for Energy Saver settings, I've set my Air to go to sleep in 3 hours, with my display sleeping in 1 hour. This is obviously when my Air is plugged in. Any insight as to why my fans kick in? Is it the screen saver? Thanks in advance.