On Mon, 17 Jan 2005, Lennart Augustsson wrote:

> I doubt the PCI bus itself is noisy.  But your sound card could
> very well be picking up noise from other parts of the computer.
> It's a very hostile environment for analog electronics.

I agree. The culprit is the design of the pc backplane and insufficient 
decoupling on the card. I had the same (and worse) problem with most 
soundcards. Only high end soundcards which have galvanic separation and 
separate grounds for outputs do not have this problem. The noise problem 
is particularly obvious if the computer sound output is wired into a 
HiFi amplifier and the sound output is muted. On one card I could hear 
the mouse interrupts (move mouse = hrrrr)!

Peter