[Night_Thastus]

Sigh, it's almost like I had this conversation before.

My audio equipment is not connected by USB. It's connected by optical (TOSLINK) to an external DAC. TOSLINK is not great, but it shows that it is not a USB noise problem.

[Yeask]

If you had that conversation before and you still having noise, maybe you are not doing the right thing... Sigh...

[Night_Thastus]

I got rid of the noise via the method I described in the original comment? Moving my audio equipment to separate power strip on a separate outlet. It didn't totally remove it, but made it quiet enough to deal with.

[butvacuum]

Don't mind them. I've had a similar thing happen, but with power line Ethernet. In your case however, I'd be at least a little concerned about the building wiring.

[Night_Thastus]

I ran into a similar problem! I briefly used CAT6, which is required to be shielded.

That shielding was carrying noise from my PC, through the network switch, to my raspberry pi that I used for music streaming. Absolutely nuts.

I swapped to unshielded ethernet cables and it went away.

As for building wiring, this issue has persisted in multiple buildings.

[hunter2_]

In many analog pro audio applications, it's actually recommended that a shield be connected at one side only, for this reason. By convention but not necessarily necessity, the bond is typically kept at the receiving end, as that's almost always a device with a grounded power cord (such as a mixer). Many DI boxes feature a ground lift switch as a convenient way to achieve this. But you wouldn't want to disconnect it at both ends, as then the shield has no effect at all.

Anyway, if you had problems with your unshielded cables that would be solved by a shield, but your shielded cables caused a different problem due to the bond at both ends, this technique of using shielded cables but severing the shield at one end of them would get you the best of both worlds.

[typewithrhythm]

Huh, I had no idea that cables would have their shield grounded at both ends... Single point ground is such a standard in electrical design that the guidance is generally "do otherwise only if you have the ability to make many prototypes to nail RFI issues".

[butvacuum]

Ruled out the monitor(s)? There's been cases where they've backfed power, and they certainly backfeed EMI as well. And, it could also be tied to FPS- assuming gsync/free sync.

If you have a multimeter its probably worth double checking if the case is low resistance grounded to the end of the cord. I'm assuming you have checked already, but as a shock hazard it bares repeating.