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Date: Mon, 9 Jun 2008 11:12:00 +0200
From: cpghost <cpghost@cordula.ws>
To: James <james@icionline.ca>
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Cc: freebsd-questions@freebsd.org
Subject: Re: Whine when EHCI controller enabled in BIOS
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On Sun, 8 Jun 2008 21:40:17 -0600
James <james@icionline.ca> wrote:

> I have a high pitched whine coming from my motherboard when the EHCI
> USB 2.0 controller is enabled in the BIOS.  The whine only starts once
> FreeBSD 7.0-RELEASE is halfway through booting.
> 
> The whine also goes away when I plugin a USB drive in with EHCI
> controller enabled (usb keyboard and mouse being already plugged in).
> 
> Is this a hardware problem, or could it possibly be software
> related???

Hard to tell. I've had whining EPIA-boards when run at 1000 Hz,
and after switching kern.hz to 100 Hz in /boot/loader.conf, the
high-pitched whine stopped entirely. It also stopped when I
slightly deviated from the 1000 Hz (to, say, 900 Hz or 1100 Hz),
so there was obviously some hardware component on the boards
oscillating like mad at this very frequency.

I'm no specialist and it may be an urban legend, but from
what I gathered, some coils could exhibit the behavior of
generating those high-pitched whines when exposed to certain
frequencies.

-cpghost.

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