GPU interfering with sound output?

[SKaRT]

I've just upgraded to a Gigabyte 480GTX SOC and since doing so I'm getting a constant buzz come through my speakers/headphones. I have an Asus Xonar D2X and I have also tried with the onboard sound - both cause the same issue. The only way I'm managing to not go absolutely insane is because I have an old USB sound card which was part of a Sennheiser headset that I am now using as a stopgap.

The buzzing is the same sort of buzz you'd get from electrical interference but it wasn't present before this upgrade and my previous graphics card was an Asus 4870x2. The old card actually has a higher power draw than the new one so it cannot be anything like it's pulling too much from my PSU.

Just to clarify this buzzing is present ALL of the time - right from POST. It also disappears for a split second when I disconnect the DVI connector from the graphics card which further tells me it's something the GPU is doing to cause this.

Any suggestions as to how to fix this or is this just an RMA job?

 

[SKaRT]

Have you tried maybe (if available) toggling Spread Spectrum in the bios? A longshot solution perhaps but a free one. Maybe try to only have one sound source too, ie, disable both onboard sound and Nvidia HD Audio. Maybe a coincidence but seeing as it goes away when you remove DVI cable, maybe the cable is dodgy? Not familiar with your GPU at all, but can you try a different socket? Or standard VGA perhaps?

No such option in my bios for spread spectrum. Disabling/enabling the second audio output has no effect. The output from the graphics card is also not the issue because the sound is still there even with nothing connected to the card.

Remove and reseat your addon cards. Make sure none of the backplates are touching each other or something they shouldn't.

This was the first thing that I had checked when I first started hearing it and there is nothing touching anything else.