Alright, been sitting on the sidelines but here is my 2 cents as someone who has owned 5 Studios M1/Max/Ultra and now a M2 Ultra.
There are two noises folks described over the past year since release.
Fan Noise-
This was set at a particular speed by Apple for the M1 variance, I believe around 1300 rpm. Some folks could hear it depending on their environment. (I.e. how quiet the room is, or where the Max was positioned if it had room to bounce the sound etc) ALL MAC STUDIOS HAVE THIS NOISE. (In my experience and basing off the fact that it was correlated to the fan.)
Some folks didn’t like that, clean fan noise doesn’t bother me because it’s like white noise.
Enter the next noise— what folks described as coil whine, or a whistle, HIGH PITCHED NOISE.
This, was different than the fan, and it seemed like it was only evident in some Studios, regardless it was correlated to the fan speed. I’ll explain.
Folks (including myself) were able to get rid of this “whine” by lowering the fan speed to around 1100rpm etc (funny enough that’s something Apple did with the M2 tah dah!)
My favorite way to prove it was the fan and the grill holes in the back causing it was done by this gent
basicappleguy
He just put tape over a section of the grills in the back and the noice went away. I was able to reproduce this using a sticky note.
Now DOES EVERY STUDIO HAVE THIS HIGH PITCHED NOISE???
Here is where I’m only going to opine since I don’t have the metrics for it.
I believe only some of them have this, but this is further complicated by variances in folks hearing health and environmental factors
Some people just can’t hear that high pitched frequency. Other folks just don’t have a desk that’s up against the wall where the sound can bounce off, or have a refrigerator that emits a sound that would mask it etc etc etc.
My personal opinion as to the cause: I am not a hardware engineer so take it as literally an opinion. I believe this there is enough variability in the grill/holes manufacturing of the M1 Max that some were more susceptible to causing the sound. There are a ton of holes in that grill and consistency and QA I can only imagine is challenging. Particularly in the Max which has the softer aluminum cooling VS the Ultras Copper.
So my recommendation. Get the Studio, if you hear the noise and can’t ignore it, return it and try again. If you don’t want to deal with that, play with the environment see if that makes it better.
My report of the M2 Ultra is this, the fan is noise is clearly lower, and the “whine” has not been perceptible for me. I positioned it in a way that maybe is helping but so far, I’m not going to go looking for the noise.
Hope this helps.