I've been using my MacBook Air for about 8 months (it was purchased in late 2010, hence no more warranty, and given to me as a gift), and last weekend, it started chirping seemingly randomly, seemingly coming from the motherboard, totally independent of volume control. When it happens, it chirps precisely every 30 seconds, then it stops chirping sometimes after 1 or 2 chirp, sometimes after 10 minutes. I have searched high and low on the net about Mac chirp/beep, listened to all those mac beeps on youtube, etc. and mine doesn't sound like any of them. It's extremely loud, and the chirp itself is very short. I can't remember what I was doing the first time it chirped. For a while I thought it was usage related, but can't identify any specific program/files, but then I realized it was chirping even during hibernation, and even when the computer is completely turned off with the power adapter unplugged!! I ran all the disk utility and hardware check and such and everything was fine. I took it to an Apple Genius Bar, and the genius was totally baffled by the whole situation and why it would beep even when the computer is off. He ran all the quick and dirty checks they do there and everything was in working order. And of course while I was there the computer refused to make a single beep... He didn't think it was anything "serious", but suggested I could leave the computer overnight and have them stress-test it. I didn't do so only because I'm rather reliant on my mac and since it still worked I figured I'd just wait it out and see. Over the past week, the chirping seems to have increased in frequency. Today when I came home the darn thing was chirping (while turned off) and hasn't stopped chirping since I turned it back on, now probably 20min and counting and it's still chirping every 30 seconds. I think this is the longest it has chirped. The computer itself runs absolutely fine, no error messages, no random shutdowns of programs, nothing. Except for this annoying chirp. Any help/suggestion would be greatly appreciated.