MacBook Pro Special Report: High-pitched whining noises: Eliminating

CNET staff

Sept. 2, 2009 6:31 a.m. PT

5 min read

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

There appear to be various causes for this issue, and various associated workarounds.

In most cases, the problem has to do with power draw. When a certain amount of power is being drawn, the problem manifests. 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).

In some cases, whining sounds of this nature are related to the tied to screen brightness and caused by defective inverter boards. 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.

Another noise seems to be associated with a fan located under the right side of the MacBook Pro's keyboard. Most users say the noise sounds like a fan is trying to startup then fails several times in a row. Some users have described the noise as akin to the "mooing of a distant cow."

MacFixIt reader Mortel writes:

"If I use my MacBook Pro for a while, a noise coming from the right side that sounds like a fan is trying to power up, but fails, tries again and again. Normally I would suggest that when the MacBook gets too hot, the fan powers up and runs for a while (when I start a game it works fine). But in the case of normal work (iDVD, iMovie, iTunes ) the fan just tries to start several times."

Most users who have experienced this noise issue have run Apple's Hardware Test CD with no error messages.

Fixes

Turn on iSight Several readers have reported that turning on the MacBook Pro's built-in iSight eliminates the whining noise.

One reader writes:

"Hi, i have the same problem. When i turn on the webcam the noise disappears, but when the webcam turn off, the noise starts again."

One easy way to turn the iSight on quickly is to use the Mirror widget, simply activating Dashboard whenever the noise becomes apparent. In fact, some users have reported that turning on the iSight temporarily then turning it off results in a lasting elimination of the noise (until the next restart).

Plug in power adapter Some users have reported that the noise goes away when the MacBook Pro is connected to an external power adapter.

Adjusting screen brightness In one variation of the problem, the sound can be eliminated by turning screen brightness to the maximum level, though in-house we found that doing so resulted in emission of a different, yet equally annoying high-pitched noise.

Wait a few days In-house our MacBook Pro suffers from a version of the whining problem is solved by turning display brightness down to zero. Other readers indicate that after a few days of normal operation, the sound goes away. It may just be a side effect of the system being "broken in."

Try tilting the display back and forth a few times Several readers have reported that tilting the display back and forth, or gently squeezing on the screen casing's lower left corner eliminates the noise.

Turn off ambient light sensor MacFixIt reader, Michael, reports that turning off the Ambient-responsive keyboard lighting (go to the "Keyboard and Mouse" pane of System Preferences and uncheck "Illuminate keyboard in low light conditions" resolved the issue:

"I just wanted to chime in. I saw the suggestion about opening and closing the display and noticed that it would stop and start again as the ambient light under the keyboard would turn on and off. On it would whine, off it would stop. So I turned on the room light, the ambient light turned off and the whining stopped. So for me, anyway, the ambient light is what causes the whining."

Turn off one processor core Though not a viable long-term solution, some users have found that turning off one of the MacBook Pro's processor cores eliminates that noise.

In order to turn off one processor, you need to install Apple's Developer Tools (from the install discs included with your MacBook Pro). You will then have access to a System Preference pane labeled "Processor" that can toggle between single and dual-core operation.

Turn on Bluetooth Some users have eliminated the whine by activating Bluetooth then using one or more Bluetooth devices. This workaround reiterates the notion that most cases of whining involve power draw issues.