# mobo shrieking sounds



## Ghirai (Mar 16, 2010)

Hi,

I have a P55 chipset mobo, that makes shrieking sounds in FreeBSD 8.0 *only* (edit: also tried STABLE).
It doesn't happen in Windows, nor in 7.2.

The shrieking starts during the boot process at these lines:

```
SMP: AP CPU #x Launched!
```

It doesn't matter if powerd is running or not, nor does it matter what the minimum frequency is (i tried them all). The shrieking sound only stops briefly when the system is in full load. Also it varies with mouse movement.

I'm pretty confident that the sound comes from the coils that are part of the CPU voltage regulator, situated near the CPU. Nowadays they are inside little black plastic boxes. I remember that some crappy older mobos had this issue when the coils were exposed.

Any ideas? I've tried everything, including adjusting voltages in BIOS. The mobo is a MSI P55M-GD45, and CPU is Intel Core i5 750.

Again, the issue not present in Windows, or in 7.2 :\


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## Beastie (Mar 16, 2010)

A random idea: try `# sysctl kern.hz=100` or similar.


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## Ghirai (Mar 16, 2010)

Thanks, that seems to make a slight difference - the pitch is lower and a bit less annoying, but it's still there.

Any ideas on what's causing it, and why it only appears in 8.0?


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## brucec@ (Mar 16, 2010)

On my system I think it went away when I disabled some power management feature, possibly C1E or EIST.


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## Ghirai (Mar 16, 2010)

Thanks, disabling C1E did it.

I'm still curious to know why this is happening on 8.0...


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## mav@ (Mar 16, 2010)

This sound probably originated from some on-board power converters. C1E and deeper C-states create more significant power spikes. May be at some pattern they make ferrite cores resonate.


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## Ruler2112 (Mar 17, 2010)

The real reason of this is the same reason that makes junkies suffer withdrawal symptoms when they quit.  The bodies of the people using drugs are so used to being abused that they rebel when they are removed.  Similarly, your motherboard is probably used to the screwed up way windoze does things that it doesn't know what to do when a real OS is loaded and therefore shrikes in pain.  :e 


(Sorry - I tried resisting the urge to post this, but couldn't help myself.  )


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## volatilevoid (Mar 17, 2010)

Hm, I get a high pitched noise from my board and disabling EIST didn't help. Board is a Intel S5520SC, 5520 chipset, 2 Xeon E5504. I already tried the Intel forum but unfortunately, it doesn't seem that anyone there is willing to help. :\

I got an adaptor from 4 pin P4 to 8 pin ATX12V to power one CPU. Maybe this is of interest. PSU is a 700W CoolerMaster RealPower.

Sometimes the noise goes away but I don't really know why...

Any suggestions on this?

PS: Windows only ran virtually on this machine so far.


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