5D
As the title suggests I seem to have this issue, when GPU (nVidia 3090) is doing stuff. For example moving viewport around.

Very strange, done alot of searching for help on Google to not much luck.

Posting here cos Houdini (possibly) seems to be part of the problem?

Am I going mad??!!!!

you didn't describe the noise but

that's normal see if you get the same noise in other programs (3dcoat viewport should be noisy as hell)

its coil whine, either from motherboard, GPU or PSU, you got unlocky, not sure if you can RMA this, I did and got a new more silent GPU card

in one case I saw the coil whine being persisent and noisier when there is not enough current to support the GPU, the PC may shut down immediately
its rare, probably just coil whine as mentioned above, lots of people don't bother with the noise, especially gamers who use headsets

try RMA the GPU, probably you won't get a new card (its tricky), you can also try change motherboard or PSU, if nothing helps its normal behavior and lots of people made peace with it

So with help from my friend we discovered that the input grounding point on both KRKs had intermittent issues when the jack was not located in an exact location showing possible dry soldering points in the input stage.

Going to change out input sockets another day when possible.

Hi 5D,
what means "grounding Point KRKs"?

I have the same problem with my 3090.
The spool(coil) makes the noise for me.
It only occurs when working with Houdini.
And I think the problem exists since the graphics card driver update (531.18).

https://www.russandrews.com/images/pdf/Grounding%20Article%20Mk4links.pdf [www.russandrews.com]

what speakers are they???
i think the problem is always with the speakers if you have a decent GPU

though i still get this problem, just less. KRKs are monitors. speakers for the studio.

Maybe we have different problems.
At first I thought the noise was coming from my computer's internal speaker.
But it's definitely just the coil of the graphics card (RTX 3090).
When I move in the viewport, the coil of the graphics card hums.

oh def different probs, seems clear now. good luck!

Have same issue. Strange buzz appears only when moving objects using handles in viewport. It's defenetly sound from hardware, dunno ist it videocard or else, but seems very strange. Hardware - Laptop RTX 3060, I7, have a latest nvidia studio driver 551.61. Does anyone have a clue on what is that can be?

MinistryofSpaceandTime
Have same issue. Strange buzz appears only when moving objects using handles in viewport. It's defenetly sound from hardware, dunno ist it videocard or else, but seems very strange. Hardware - Laptop RTX 3060, I7, have a latest nvidia studio driver 551.61. Does anyone have a clue on what is that can be?

Coil Whine.

If it's a high-pitched sound coming from the GPU itself when it's active, it's most likely coil whine. If it's noise coming from your speakers while it's active, you may have a possible ground loop. Unfortunately we can't do anything on the software side to fix a physical issue. Ground loops can be tricky to track down, so it's best to read up on them and perform some experiments. This is a pretty common issue, so you should have no trouble finding some guides or tips on how to do so.

I've personally had this issue, and it's maddening. I wish you all the best in your search for a solution!

Well, if you are moving the viewport, and the noise usually comes from you GPU.
The noise comes from the ceramic capacitors on your GPU's power supply rail. Ceramic capacitors have piezoelectric effect. Meaning if the power supply voltage fluctuates (ripple), there will be sound coming from the capacitor. The construction of the ceramic capacitor cause this effect. The power supply controller on your GPU controls the power supply voltage. Under heavily or full load, the voltage ripple's frequency is very high. You can't here the noise from capacitors. However, in idle state, the load is very small, the controller has to wake from sleep, do some work and fall sleep again. The ripple frequency is low, so you can hear the noise.
When you move the viewport, your GPU experience some idle -> heavy -> idle load state. And because the viewport is not a so heavy load, the duration of heavy load is very short, which makes the noise even noticeable.

Put the power cable for your speakers into a different outlet.