"Grinding" and other digital noise through speakers

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Joined
14 Nov 2022
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68
Location
Leeds
So, rewind to almost this time last year. I had upgraded my AM4 platform replacing the Ryzen 5 2600 with a 5600 and added an AIO and an RTX 3060ti FE. In June this year i changed case from the NZXT H510 to a Fractal North. My setup is my PC connected via USB to a Focusrite Scarlett 4i4 audio interface which is connected via balanced cables to two Yamaha H5 active speakers. Somewhere around this time if not a little before i noticed a faint "grinding" sound in game (which varies depending on in game location/ view) and at this time it was just in game coming through my active speakers. I put it down to maybe a windows update, or something that might be game related. A couple of months back however and to date i have noticed mouse sounds (scrolling etc) together with a constant low level digital sound also coming through the speakers which is not affected by volume changes. This sound is present in BIOS as well as in Windows btw. Also i am pretty sure the in game noise has worsened.

So i ran a "few" checks (these are the main ones):

  • Replaced the GPU,
  • Replaced the PSU,
  • Disconnected all non essentials,
  • Tried all other USB ports for my external Audio Interface (which is bus powered),
  • Tried a different USB cable,
  • Tried another Audio Interface (external powered),
  • Tried a powered Hub,
  • Tried without cable extensions,
  • Directly plugged in speakers in audio out of the PC,
  • Tried other sockets in other rooms,
  • Replaced the power bar ensuring everything was plugged in on the same strip,
  • Tested Interface and Speakers on another PC,
  • Rebuilt my PC,
  • Reset BIOS and turned on and off the feature sets,
  • Performed numerous driver updates,
  • Used a socket tester on the wall and extension sockets,
  • Changed screws for mobo and PSU to non painted ones.

The only things that resulted in this sound vanishing were the following:

  • Disconnected Active Speakers from interface (just standard active speaker hum).
  • Connected a Laptop to the interface and speakers.
  • Connecting a DI in between interface and monitors and using "ground lift" (which also cut the volume level in general)

I am now looking at my motherboard suspiciously. It is a B450 from 2018 so the oldest item in my rig and i do wonder whether it is passing on this interference. I did initially wonder whether this was a ground loop issue, however aside from component change in the PC all the power/ USB/ audio connections are the same as before.
 
Sometimes the case isn't earthed properly at the power supply. If you have a multimeter, turn the pc off/unplug for 15 minutes and check the earth pin on the iec input. It should have continuity with the motherboard io plate (and any exposed metal in the case). It should legally also be under 1 ohm in resistance (likely far lower).

Sounds like it's graphics card related if it varies when looking around in-game. Also possibly a bad monitor/cable (hdmi/dvi etc). Does the noise disappear if you unplug the monitor? If not, try opening ms paint full screen and fill it black. Does that change the noise? Toggle back to white and see if you hear a change.
I will check continuity at the weekend and the also the MS Paint suggestion. I can also re-check the monitor and cable which are new items introduced after i discovered the noise. It certainly is related to GPU activity having run a CPU stress and finding no change to the sound. When i swapped out the 3060 ti for the 1070 the sound was still present in game/ Heaven test, however it was not as present.
 
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