You should check if all jacks and cables are ok. If this shouldn't
solve the issue, I wouldn't spend time with fixing such an issue.
Without changing anything the phones output of my RME PCIe card changed
from quasi no noise to noise as loud as the audio signal, from one day
to another and I never god rid of it again. You changed your hardware
and the audio device is an onboard elCheapo device ;).
Audio devices don't belong inside a computer. I don't know what
does cause the issue for my RME audio card, perhaps a fan aged
or some hidden shielding is broken, at least the audio cables are ok.
However, don't waste your time with trying to fix issues cause by an
integrated elCheapo audio device, instead get a replacement, some audio
device for less than 50,- EUR most likely does sound much better. IMO
even spending time for fishing returnable bottle out of public trash
bins, to get the money for a new sound device, is less wasted time,
than spending time with trying to fix the noise issue. YMMV!
At the moment I try to replace my audio card, by an external, too. I
already have got the money, but still don't know what device to order.
Seemingly a lot of people experience xrun alike issues with USB
devices :D.
Regards,
Ralf