Farty MBP...
March 29, 2010 4:17 PM   Subscribe

Weird MacBook Pro behavior... It seems to fart when I move it.

Ok so it's not exactly a fart. It makes a single soft, mid-pitched click/beep from time to time when I move it around. It's low volume, and I'm unable to reproduce the behavior consistently, nor do I know for sure if it's coming from the speakers or elsewhere, or if the set speaker volume has any impact. I think it comes from the right side of the machine (again, speaker perhaps). I have never heard the sound during the use of any program or been able to associate it with any running process. It seems clearly (though inconsistently) related to actual movement of the machine.

This is a unibody 15.4" MBP (mid-2009) if it matters. The computer is otherwise perfectly functional. Anyone else had this or been able to explain it?
posted by drpynchon to Computers & Internet (14 answers total)
 
Does it have a conventional rotating platter (not SSD) hard drive? If so, it could be spinning down/parking heads in reaction to the movement.
posted by scatter gather at 4:23 PM on March 29, 2010


Yeah if I set my macbook down on the desk fast sometimes I can hear the disk head park. I'm pretty sure its because I am triggering the sudden motion sensor.
posted by Captain_Science at 4:25 PM on March 29, 2010


I hear it too. I assumed it was part of the anti-shock protection feature which is supposed to kick in when you accidentally drop the laptop.
To me it sounds like the laptop is saying "Hey I know you're walking around with me. Don't drop me, k?".
posted by special-k at 4:26 PM on March 29, 2010


Sudden motion sensor.
posted by special-k at 4:31 PM on March 29, 2010


You learn something new every day.. Thanks guys..
posted by drpynchon at 5:13 PM on March 29, 2010


hmmm.. never noticed it, mine does the same thing... and, thanks to you, I'll now consider it a tiny mechanical fart....
posted by HuronBob at 5:50 PM on March 29, 2010


Hey, I've been wondering about the very same thing, so I'm glad to know what's up. For me, I've noticed it when the heel of my right hand hits it while I'm typing!
posted by lunasol at 6:14 PM on March 29, 2010


The only thing that doesn't add up is that on my prior generation MBP (2006 I think) I never heard this. Perhaps both the original and aftermarket drive I put on that computer were just quieter or better insulated.
posted by drpynchon at 6:40 PM on March 29, 2010


...on my prior generation MBP (2006 I think) I never heard this...

Exact same thing for me. I never heard this on any of my previous Mac notebooks, but it's very noticeable on my new 13" unibody MBP. It's the only thing I don't like about this computer.
posted by joshrholloway at 7:47 PM on March 29, 2010


For me, I've noticed it when the heel of my right hand hits it while I'm typing!

Bonus Answer: there's a plugin you can get (forget what/where...i'm sure google knows...) that lets you control iTunes this way with the sudden motion sensor...tap it on one side of the trackpad to advance a song...great for when shuffle craps on you...
posted by sexyrobot at 9:01 PM on March 29, 2010


My MBP does this too, and I'm pretty sure it's a fault. The motion sensor shouldn't be that sensitive, and mine made a loud click every time you picked the damn thing up.

In the end I disabled the SMS entirely, which you can do with this command:
sudo pmset -a sms 0

I disabled mine a year ago and haven't had any problems since.
posted by Mwongozi at 1:22 AM on March 30, 2010


Mwongozi; That's really a terrible, terrible idea. The rotational velocity and tight tolerances in a disk can easily be overcome by small amounts of motion in the right (or, wrong, depending on your perspective) motion. If the head hits the platter you stand to lose every single thing stored on your computer. The minor inconvenience of a ticking sound every now and then when you move the laptop seems a fine tradeoff for potentially parking the head when it wasn't necessary.
posted by odinsdream at 4:50 AM on March 30, 2010


odinsdream: Sure, I'm aware of the risks, but my SMS was *way* too sensitive. For example, if I had it on my lap and coughed, then the disk would park with a loud click.

It's been off about a year now, and have had no problems. Sure, maybe my disk will die early, and if it does, I'll replace it. Disks die. C'est la vie.
posted by Mwongozi at 5:13 AM on March 30, 2010


SMS disk parking doesn't prevent mechanical failure through regular use of the disk, it saves your disk from entirely preventable head crashes as a result of physical movement. Literally the only downside is the tiny click noise and a few milliseconds of delay in reads or writes during the park/unpark.
posted by odinsdream at 3:26 PM on March 30, 2010


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