G35: crosstalk from integrated GPU to sound chip

[Maxim Levitsky]

On Sunday, 8 June 2008 15:25:32 Rainer Dorsch wrote:
> Hello,
> 
> I am running Debian lenny on a G35 chipset (ASUS P5E-VM HDMI) and I observed 
> that the sound chip (?) picks crosstalk from the integrated GPU.
> 
> It continously picks some noise. When one or several blocks of the screen 
> change, I can hear a "clack" sound. Also when I run glxgears the noise level 
> increases significantly.
> 
> The noise does not change when I plug off the DVI/HDMI cable at the computer 
> or when I use a headset instead of the speakers. Thus I think the crosstalk 
> happens inside the system. The glxgears setup indicates that it has something 
> todo with the integrated GPU.
> 
> Anybody seen something like this before?
> 
> Any suggestions are welcome.

I guess this is normal _if_ your sound card supports so
called analog loopback (= you hear what is on its inputs)
and you set input gain to maximum.

If I do so, I can hear lots of things, like moving a mouse, running infinite loop
on CPU, accessing hard disk, etc...

I guess that everything is connected via ground, thus some small crosstalk is normal.

I have seen this on several PCs

Best regards,
	Maxim Levitsky