Can PC hardware affect internal audio capture?

Question

Put another way, if I'm having some audio output static issues, and I record my internal desktop audio using something like OBS, virtual audio cable, or stereo mix, and the static is present in the file (eg I can send it to another device and still hear it), does that rule out hardware issues (like soundcard/speaker problems)? I think it would rule it out, since I assume that internal audio capture just captures the digital signal being fed to the soundcard/speakers, so the hardware wouldn't have a chance to affect the signal yet. But that's just a guess because I couldn't find much information online about how internal audio capture actually works.

Answer 1

It's usually Radio Frequency interference [RFI].
Note that many people will claim it's a "ground loop" but this is actually very unlikely. It's leakage, though it will never hurt to make sure a desktop is correctly grounded [earthed].

There's little you can do about it, as it's often down to the manufacturer cutting corners.
If you have any peripherals connected, try without them [right down to trying a wired mouse instead of wireless]. If a laptop, try on battery power rather than mains - the PSU can contribute with high frequency 'spill'; very common in modern switch-mode power supplies.

For a desktop you can sometimes mitigate this slightly using an external USB sound card - simply by moving the DAC away from the internals you get a bit of separation. If your entire routing is internal, this will only help if the noise is being picked up inside the DAC rather than before it. As your interference is in a file generated entirely inside the machine, I doubt it would help.
Trying to track down which components are responsible is likely to be an unfruitful search. Anything with high frequency switching could be responsible & should have been RF damped by the manufacturer.