Notes on MacBook Pro Whining Sound

At least some of the MacBook Pros seems to have a persistent whining sound when the machine is idle. Some people say they haven't heard anything, but the sound is very real on mine. I'm told my hearing is more sensitive than average, so some might sit in front of the same machine and not be bothered by it.

Unchecked, though, this sound would make it impossible for me to work. The quieter the environment, the more noticeable it is. I hope Apple comes up with an OS or firmware-level fix for this soon, but in the meantime, there are a few observations that I think are worth mentioning.

(One simple solution, by the way, is to disable the second core using the CHUD tools, but that just seems silly when you've paid for two full-time cores.)

1. The sound is not present all of the time. As others have mentioned, even a small bit of base level activity on both CPU cores seems to nullify the sound. If an open application has activated the iSight camera, that seems to negate the issue as well. This might be a side affect of using some cycles in the background, but it could also be a separate factor. The sound is also not present at boot time.

2. If I don't touch the machine for about 15 seconds, the sound drops off considerably. As soon as I touch it again, the sound returns. This is at least the case when running off the battery, haven't tried it with AC power.

3. I don't have a degree in electrical engineering, but based on my very limited experience it feels like this is some sort of electrical/magnetic interference issue. Maybe the magnetic power connection affects this somehow? Maybe not. Stretching my already tenuous knowledge in this area, having both cores active might just be enough to tip the electrical "balance" in the proper direction.

Using this as a theory, I tried to tip the electrical balance in the machine a bit more by plugging my (fifth generation) iPod into the USB port, which draws power from the USB bus. Sure enough, this silenced the thing almost immediately. Even when the iPod is unmounted and both cores are idle, the whining is completely gone.

So there's today's tip. Maybe we have some EE dude who can use that to form a hypothesis. Daniel Jalkut also has some experiences with this.
Design Element
Notes on MacBook Pro Whining Sound
Posted Mar 23, 2006 — 22 comments below


Daniel Jalkut — Mar 23, 06 953

The iPod workaround you observed is similar to some comments that have been made on the Apple discussions forums. There, people have claimed that plugging in a USB flash drive has silenced the noise. With all these workarounds, it certainly does seem like Apple can at the very least come up with the most efficient of them all and institutionalize the fix.

Scott Stevenson — Mar 23, 06 954 Scotty the Leopard

I justed plugged in a cheapy USB 2.0 card reader and that seemed to do the trick. By contrast, I plugged in a USB 1.0 flash drive last night and that didn't help at all. Hmmm. More clues.

Adrian Cooke — Mar 24, 06 959

In case you hadn't seen this post by John Siracusa… It's mostly about the Dual G5 but he mentions the MacBook Pro as well.

Keith — Mar 24, 06 962

Daniel Jalkut over at Red Sweater Blog recently covered this exact issue fairly well, and even whipped up some code to take care of the whine: All Work and No Play Makes a Quiet MacBook Pro. Looks like he's posted a followup article just now.

/me wanders off to read it.

Mark — Mar 24, 06 966

Unfortunately all of the software workarounds (and probably the USB key / iPod trick) "work" by increasing the current through the processor. The Red Sweater Blog link above has some specific details regarding why this is so--the additional load created on the machine by these various techniques is preventing the CPU from entering certain sleep states. This ultimately affects your battery life.

My battery life with whine and no workarounds is 3:30-3:45. Using the software workarounds, it is reduced to ~2:50. This is a very significant dent...especially if I'm just sitting in class taking notes!

For those interested, I started a whine poll. The results are becoming a little more interesting since we've captured over 300 MacBook users so far. I've been receiving some requests for different charts so the data can be analyized better, so it is always improving. Please stop by and fill it out when you have some time.

MacBook Pro Whine Poll

sjk — Mar 24, 06 972

Is it possible the internal iSight's use of USB is making it a successful workaround for the same reason as using certain external USB devices? Has anyone done the same with external FireWire devices? Just wondering if/how USB-specific issues are influencing the problem.

wasp — Apr 03, 06 998

i am on my third macbook replacement from applecare - i haven't received the third as it is week 13 - but should arrive tomorrow. - the other two both exhibited the whine

Alex — Apr 04, 06 1001

I found a solution for the problem, it is probably not the best solution but it work on my machine.

On the terminal just write this:

mkdir /backup
sudo mv /System/Library/Extensions/IOPlatformPluginFamily.kext /backup

then reboot.

the whine disappear on my macbook.



Scott Stevenson — Apr 04, 06 1002 Scotty the Leopard

sudo mv /System/Library/Extensions/IOPlatformPluginFamily.kext /backup

This seems to cut the battery life in half?

Alan — Apr 09, 06 1091

Alex and/or Scott could you further explain any resulting side effects of that command line.

Greatly appreciated.


Scott Stevenson — Apr 10, 06 1092 Scotty the Leopard

Alex and/or Scott could you further explain any resulting side effects of that command line.

My educated guess is that it's robbing the power manager of the ability to determine what model it's working with so it just stops trying to throttle the power supply, thus silencing the whine.

Jeff — Apr 10, 06 1094

Interesting.. I've not noticed a whine on my 15" Pro, tho I did notice that you can make the thing sound like a lightsaber if you hold the thing in your right hand and gently (but quickly) swing the left end up.

it's kind of odd.. I figure it must be the anti-vibration/drop thing halting the drives or something.. it's kinda weird tho.

kbap — Apr 24, 06 1128

I am on my second macbook replacement (w8615...) from apple, and this exhibits more whining symptoms than the last. another funny symptom is exhibited when using the expose features, front row and dashboard. the sound made is like a flickering sound, when i use the photobooth fix or any other intermediate fix this issue is also fixed along with the whining!

Pistachio — May 01, 06 1150

Fuck the WHINE I took it in to the Apple store to get it fixed and they had it for a week and when I got it back it was exactly the same, and they said it had no problems even though I told them it had to be quiet 2 hear but that it was really annoying while doing HW. I think they racially profiled me.

zolt — May 04, 06 1166

After reading about how the core processors disable certain portions of the processor based on need, this definately sounds like an electrical interference problem that is the fault of the intel core processor, and probably has nothing to do with apple's design. Processors ususally run at higher frequencies than are audible, but I'll bet that during mostly idle times there are certain parts of the chip that are cycling on and off at frequencies that we can hear. If this interference is strong enough to make audible noise then I wonder if it is also the cause of the airport connection problems that I have heard about. I'm willing to bet that apple will not be able to fix this problem without hosing the battery life.....that is until intel respins the chip and comes out with a rev. b version.

Anon — May 11, 06 1205

Sounds to me like capacitor whine... this is a problem endemic to switching power supplies (such as the kind used all over a motherboard, and inverter). This is probably from trying to make the machine too light - they used too small of a capacitor in the power supply, and the voltage ripple, while within electrical specs, makes the capacitors act like speakers (tweeters, specifically).

The solution would be to re-work the boards to add an extra damping cap to certain power busses on the board (that is, if the buses aren't buried in the middle of the board, and they can get to them), and add this to a rev B board.

Processors, themselves, are seldom the direct cause of audible whine - it's the caps that are mechanically resonating with the voltage ripple (but, the processor switching it's current consumption at audio frequencies can induce that voltage ripple -- so, changing the processor's load can change the ripple on the power bus).

The other thing that can happen is (depending on the design in question) when a switching power supply is lightly loaded, it's switching frequency changes, and can reach a frequency that the caps in it resonate with - so, just plugging in a USB memory sick (or some such thing) can change the loading on the power supply enough to kick it out of the resonant frequency. Also, the frequency can change with changing input voltage, so I wouldn't be surprised to see (er, hear) the whine come-and-go with varying battery levels.

Jack — May 11, 06 1207

Ben — Sep 19, 06 1827

My MacBook Pro also suffers from the whining nosie, but I've noticed that the noise is not present if I boot into Windows XP.

Eldho — Nov 16, 06 2420

This is indeed capacitor whine. I hear it on my Dell machine. However, the cause of the problem is not quite the switching noise. The CPUs have advanced power states that allow the voltage to the CPU to be lowered for a few milliseconds to save power. This is why the "fix" is to stress the CPU enough to prevent it from entering these lowered power states.

The caps bypassing the cpu voltage physically changes its length slightly depending on the voltage expressed across it. WHen the advanced power management changes this voltage, the cap changes its length accordingly. When this happens at the right intervals, acoustic noise is created.

I am going to try putting epoxy or some sort of glue that "holds the cap from vibrating".

So its not that they used cheap caps, but that this new power management scheme was introduced.

To fix it, they would have the place the caps in such a way that these vibrations cancel out - this means whole redesign of MB.

Guy — Jun 12, 07 4334

I run folding@home to make it go away, of course that gets the fan going which is a totally different issue!

Patrick — Sep 18, 07 4611

Apple replaced my MBP (core duo) motherboard a year ago for this problem and that fixed it in '06. BUT, I took my Mac in to replace a fan and they switched the MB too. Now, the problem is back! Assuming they didn't put an older MB in, there's still a problem in '07. I wonder if it is present in a certain percentage of MB's and in my first repair they were careful and checked the noise since it was my complaint that time. I'll give the Apple part #'s in case people are interested.
630-7705 previous, no whine
661-4044 current logic board whines

Has anyone successfully intervened physically with either sound dampening or putting epoxy on some capacitor(s)?

Pete — Sep 25, 07 4646

I have an old Compaq notebook with the same whine problem. I am going to use it as a test machine - I will try putting epoxy on some of the caps round the power supply area. Then if it works, I can move on to my MBP.


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