This may be helpful as it was for me. I copied this from another discussion member. I can't his original post anymore so I hope he doesn't mind:
"Apple has already acknowledged the "whine" problem and has been replacing models with the problem. Because they know about the cause of the problem - a faulty inverter - it's quite likely the problem is being addressed. It would appear that the problem is exhibited in a specific series of serial numbers.
Note the following:
A MacInTouch reader reports that Apple has two separate "bulletins" regarding MacBook problems (neither one available publicly, as far as we know):
I can confirm, at least in my case, that swapping my MacBook Pro for a model with a serial number in the W8610XXX range has eliminated the issues. My initial MBP was in the W8609XXX range. According to the nice Genius who helped me, 6 refers to the year 2006, and 09/10 refer to the week of the year the system was manufactured.
He also shared with me two separate bulletins regarding MBP noises. The first dealt with a high pitched noise coming from the upper right portion of the keyboard keyboard that varied in pitch with the changing of screen brightness. The bulletin advised this was a inverter problem and affected units should be returned for replacing. The second noise bulletin dealt with a buzz noise related to low processor utilization originating from the upper left portion of the keyboard. The bulletin stated this was normal for MBPs and all MBPs would exhibit this behavior. It went on to say that the Genius should assure the customer that it was fully within spec and that replacing hardware would not change the behavior.
In my case I was able to convince them to swap my 1st unit for a new one. The new unit does not have noise #1. And noise #2, while still present is much, much less noticeable. If I don't place my ear directly on the keyboard, I can't hear it."
MacBook Pro 2.16 (on order) Mac OS X (10.4.5) G4 Tower (OS 9/10), Dell 620 WorkStation (XP Pro), Gateway P4 (XP Home)
