On 11/01/2010 15:26, Brian Gaff wrote:
Its independent of volume and on headphones. Yes, its general whining
stuff, and does change with processor load, and drive access as far as I
can hear. I have moved some leads about and its less now, but still audible.
Obviously the psu is a heap of junk. If I could see I'd go in and put
capacitors all over the place!

It's also many other things, EMC related. If you could get done some of
the following it may help.

Place that soundcard far away from the video card, ensure the whole
length of it's backplate is well in contact with the backplane. The
small audio wire that runs between the sound card and a CDROM drive
should be one that is screened, or frankly you could disconnect it.

Also, the motherboard should be grounded at as many screw hold points as
provided. Though there is still a trend to use plastic spaces and fibre
washers to avoid incidents of nearby PCB pads shorting. So whatever.

Or the audio mixer of the card might have input sliders active, I've
come across one chipset that had a live microphone (karaoke) input
feeding into the audio playback bus!

Talking of microphones, what happens if you disconnect that cable? The
screen of that cable might be picking up hash from video circuitry, and
even though inactive might still be feeding the mush back in.

Ultimately, I'd go for using S/PDIF and an external DAC as already
covered here. Mine's a Sony MiniDisc home deck purposely stuck on
record-pause input monitor. Or, an Audio Alchemy Dac-In-the-Box DAC that
I must get around to fixing its power supply. *That* is noisy...

--
Adrian C