My machine has suddenly become very noisy - what could the problem be?

[Ant P.]

Could be a failing soundcard...

[chrisr]

Do soundcards fail in this way?

Could be a failing soundcard...

I had a video card fail once - it "went mad" on the PCI bus and prevented the machine from booting until it was removed. My soundcard's behaviour is tame in comparison... .

The noise appears to be confined to the S/PDIF channel at the moment. It might be a driver problem; if no-one connects their optical drives to their soundcards any more then this kind of bug could remain hidden.