I've had the OS X Lion Developer Preview 4 installed on my MacBook Air (Late 2010, 13" model), and have since upgraded to the GM (when it was released). I've found that since upgrading to the GM, my processor "whines" — something it never used to do before. By "whine", I mean that when scrolling through web pages or images, hovering over apps in the dock – pretty much anytime I move the cursor – there are these sounds that emanate from the usually-quiet system, which I presume to fit the description of processor whine. The sound goes when I leave Photo Booth open, but when i run other multiple CPU-intensive apps simultaneously, the sound is still present. Since the GM is the same build as the final retail version of Lion, I wasn't planning to install it. However, do any of you think that a clean installation would eliminate the above mentioned issue? It's an issue for me because I use my MBA in a whisper-quiet environment for most of the time, so this constant "buzzing" is very irritating. I read somewhere that processor whine occurs due to the low-power state of one of the processor cores, so I was thinking that it could possibly have something to do with Lion using less processor power for "idle" activities. Not entirely sure though. UPDATE: After taking my MacBook Air to the Apple Store, they decided to replace the logic board under warranty, and this has resolved the issue. Thank goodness!