# Strange whistling sound from CPU with cpufrequtils [SOLVED]

## nomind

I distinctly hear a transient whistle/hiss from my case under load with the cpufrequtils daemon on. I have set it to "conservative" to throttle it as low as it can possibly go. This is on a Pentium 4 530 (Prescott), 3060 MHz stock frequency. It manages to get down to 1125 MHz, but the whistle is a bit unnerving.

Is it possible for cpufrequtils to damage the CPU in this manner? I'm a poor college student and hence can't afford a new mobo + cpu   :Razz: 

EDIT: Sorry for not posting info. Here is the output from cpufreq-info (with the daemon off):

```
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006

Report errors and bugs to linux@brodo.de, please.

analyzing CPU 0:

  driver: p4-clockmod

  CPUs which need to switch frequency at the same time: 0 1

  hardware limits: 375 MHz - 3.00 GHz

  available frequency steps: 375 MHz, 750 MHz, 1.13 GHz, 1.50 GHz, 1.88 GHz, 2.25 GHz, 2.63 GHz, 3.00 GHz

  available cpufreq governors: conservative, ondemand, powersave, userspace, performance

  current policy: frequency should be within 375 MHz and 3.00 GHz.

                  The governor "performance" may decide which speed to use

                  within this range.

  current CPU frequency is 3.00 GHz.

analyzing CPU 1:

  driver: p4-clockmod

  CPUs which need to switch frequency at the same time: 0 1

  hardware limits: 375 MHz - 3.00 GHz

  available frequency steps: 375 MHz, 750 MHz, 1.13 GHz, 1.50 GHz, 1.88 GHz, 2.25 GHz, 2.63 GHz, 3.00 GHz

  available cpufreq governors: conservative, ondemand, powersave, userspace, performance

  current policy: frequency should be within 375 MHz and 3.00 GHz.

                  The governor "performance" may decide which speed to use

                  within this range.

  current CPU frequency is 3.00 GHz.

```

Last edited by nomind on Wed Apr 25, 2007 5:00 am; edited 1 time in total

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## Cyker

It may be the fan as it spins slower due to the lower temp...

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## eccerr0r

more likely it's the VRM making the noise from one of the inductors, with the power going so low.  It may or may not be an issue, cannot tell - depends on the motherboard whether or not it was designed to go that low power or not.  The motherboard would be first to go in this situation if something goes wrong...

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## DirtyHairy

High-pitched humming noises are rather common with electronic equipment operating at high frequencies, and are in fact (in my experience) audible from most computer systems in one way or the other (search www.thinkwiki.org for a rather original collection of descriptions  :Smile:  ). As long as they are not connected with mechanical parts (which doesn't seem to be the case for you) it should be save to ignore them (although they can become quite unnerving).

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## Cyker

Ahh, we're talking about the sort of high-pitched sonic noise that you often get when powering on a CRT-type TV, rather than an actual whistling sound then?

Yeah, it's quite common in electronics with any sort of wrapped-wire/transformer-type components.

Apparently it's due to the high-frequency causing the coils to vibrate as their magnetic field flips back and forth.

Our solution in electronics lab involved isolating the offending component and then glue-gunning the bugger to shut it up, but I'm not sure that'd be such a good idea on a PC...  :Wink: 

(And definitely not on any components that get hot!!  :Shocked:  )

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## nomind

No actually it's a very faint whistle that only appears during high load (i.e. a silly flash website or emerging an app). I'm able to distinguish it from the familiar heatsink-fan hum.

This is on an Asus P5GDC-V Deluxe mobo. I can't find much info about the voltage specifications for this particular model.

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## DirtyHairy

I second cyker, this sort of noice is produced by the deformation of ferromagnetic material in the alternating magnetic field produced by high-frequency alternating currents and your description sounds exactly like it. It is exhibited by many machines, especially when the processor enters some power saving state and may change under load. For example, my thinkpad produces several high-pitched whistling noices when on battery which depend on processor load, and the noises produced by my mac even depend on mouse movement (and no, I'm not crazy  :Smile:   )

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## ummon

I have the same CPU and had the same problem.

As far as I remeber worked everything fine with older kernel versions and cpufreqd for me. I configured an ondemand profile with frequencies between 1.15 and 3.07 GHz. Didn't remember if there was any whistling sound. 

Then with some kernel update the kernel ondemand govenor took command and my fequency only changed between 2.2 and 3.07 GHz. At that time I didn't bother why.

Recently, when I upgraded from the 2.6.19 to the 2.6.20 kernel cpufreqd got the command over the frequency scaling back an I noticed the sudden high pitched noise. For me the noise starts when the frequency gets below 1.53 GHz. I solved my problem by only allowing to scale between 1.53 and 3.07 GHz.

Hope this helps

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## nomind

Thanks for diagnosing the problem, everyone. I'll try what ummon suggested.

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