I’ve been using a MacBook Pro for about a year now, but with a growing desire to be able to swap internal hard drives whenever I feel like it, I’ve decided to switch to a black MacBook. It’s basically perfect, except for a barely audible whine (which I’m convinced most people would not even notice). I had a similar problem with my MacBook Pro, but it was a bit louder; that was solved by having the LCD inverter repaired.
I checked out the Apple discussion forums and found a weird fix that worked for me:
1) open photo booth
2) force quit (not just quit, force quit)
3) sleep (i just leave the lid open and use the menu option)
wait until you see the pulsing light and wait for a couple seconds
4) wake up quiet
If I later start and then quit Photo Booth, the whine comes back. Also, if I leave Photo Booth running in the dock, it silences it completely, and only uses 3% of the CPU (Photo Booth doesn’t show a live dock icon). But I love the Force Quit solution because it’s so strange. Link