Most users say the noise sounds like a fan is trying to startup then fails several times in a row. This was a common problem with the PowerBook G3 'Lombard' models, and the sound could sometimes be affected (or eliminated totally) by gently flexing the inverter board.Īnother noise seems to be associated with a fan located under the right side of the MacBook Pro's keyboard.

In some cases, whining sounds of this nature are related to the tied to screen brightness and caused by defective inverter boards. This explains why some users experience alleviation of the noise when toggling display brightness or turning off one processor using Apple's CHUD tools (which are included among the Developer Tools that ship with the MacBook Pro). When a certain amount of power is being drawn, the problem manifests. In most cases, the problem has to do with power draw. There appear to be various causes for this issue, and various associated workarounds.

Many MacBook Pros emit one or more version of a distinct and irritating high-pitched noise

Computer makes high pitched noise