Annoying whitenoise sound coming from snd_hda enabled chipset

[Alexander Motin]

Garrett Cooper wrote:
>     I don't know how else to describe it, but when I turn up my
> speakers enough (50%+) and don't have any sound playing, I hear a
> whitenoise hiss coming out of them. When I change webpages (nvidia
> driver is GIANT locked) or do something else kernel intensive it stops
> for a brief second, but apart from that it's an annoying trill sound
> almost like a mosquito humming around me waiting to be swatted.

I think it may be radio interference with disconnected microphone 
inputs. Try to set all unneeded mixer volumes to 0, especially mic, 
monitor, speaker and mix. Inputs often have too sensitive 20-30dB 
pre-amplifiers. Some codecs have them on all inputs.

>     It's really driving me insane... Hopefully helpful snippets follow:
> 
>     vendor     = 'Intel Corporation'
>     device     = '82801IB/IR/IH (ICH9 Family) HD Audio Controller'
>     class      = multimedia
>     subclass   = HDA
> pcib2 at pci0:0:28:0:      class=0x060400 card=0x82771043 chip=0x29408086 rev=0x02
> hdr=0x01
> 
> [gcooper at orangebox /usr/home/gcooper]$ uname -a
> FreeBSD orangebox.gateway.2wire.net 8.0-CURRENT FreeBSD 8.0-CURRENT
> #1: Mon Feb 16 20:50:56 PST 2009
> root at orangebox.gateway.2wire.net:/usr/obj/usr/src/sys/ORANGEBOX  i386

Infromation about codec or even complete verbose dmesg would be more 
helpful.

-- 
Alexander Motin