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From: "Grover, Andrew" <andrew.grover@intel.com>
To: "Troels Walsted Hansen" <troels@thule.no>,
	"Jean-Marc Valin" <Jean-Marc.Valin@USherbrooke.ca>
Cc: <linux-kernel@vger.kernel.org>
Subject: RE: High-pitch noise with 2.6.0-test11
Date: Fri, 5 Dec 2003 10:49:38 -0800	[thread overview]
Message-ID: <F760B14C9561B941B89469F59BA3A84702C93186@orsmsx401.jf.intel.com> (raw)

> [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of 
> Troels Walsted Hansen

> > itself (that wasn't there with 2.4). The noise happens only 
> when the CPU
> > is idle. Also, I have noticed that removing thermal.o makes 
> the noise
> > stop, which is very odd. Is there anything that can be done 
> about that?
> 
> I had the same problem with my Dell Latitude C600 and newer 
> kernels with 
>   HZ>100. The solution I found was to add "apm=idle-threshold=100" to 
> the kernel commandline, to disable APM idle calls.
> 
> You should monitor the temperature of your laptop to make sure it 
> doesn't spin wildly and create extra heat if you use the same 
> solution.
> 
> Using ACPI instead of APM might also be a solution?

Here's the answer from another thread:

"It's not normal, but it means they used cheap capacitors. This is known
as the acoustic noise issue. It's related to PCB vibration as a result
of the piezo electric effect on the caps. What is the timer tick
frequency? ... The 1ms gives a nice 1kHz tone. It's related to the
voltage change of C4 exit."

Regards -- Andy

             reply	other threads:[~2003-12-05 18:51 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-12-05 18:49 Grover, Andrew [this message]
2003-12-05 19:09 ` High-pitch noise with 2.6.0-test11 Jean-Marc Valin
  -- strict thread matches above, loose matches on Subject: below --
2003-12-05  6:31 Jean-Marc Valin
2003-12-05  7:32 ` Jean-Marc Valin
2003-12-05 10:31 ` Troels Walsted Hansen
2003-12-05 14:53   ` Jean-Marc Valin
2003-12-06 11:46 ` Andrew McGregor
2003-12-07 17:26 ` Pavel Machek
2003-12-09  6:46   ` Jean-Marc Valin

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