Strange distortion

A couple of weeks ago I bought a new PC (see specs below) and installed my PCI audio card. On my former PC this card worked fine, but on my new system I am getting very soft ‘distortion’ on playback of audio and when sliding volume (eg thru iTunes or Windows Media Player). I have absolutely no idea what could cause this problem. Any idea?

Could it not be the sound you are playing, as you mentioned it only happens with certain sounds/parts of the track? Ask a friend to play the track/sound, see if they notice any distoration.

Are you able to try different speakers?

Thanks.

It has nothing to do with the source sound. It does not make a difference which music I play; if I slide the volume control, there is crackle.

Even when the audio is coming from an external cd-player through line in, there is the same crackle when sliding the volume control of the audio card.

I also tried a different speaker set and head phone. No difference.

Is the power cable for the speakers connected to a surge-protected socket? try the main power socket, as I’ve read surge protection can cause problems.

The entire system is on a surge protector / ups.

its a shot in the dark but I think it might be worth it?

Tried it immediately. Unfortunately no difference.

have you tried different wires or updating the motherboard firmware?

Yep * 2