Well there is a lot you can try, I mean you can even try cleaning the electric supply as that can cause it.....no idea how, but it's a real thing. People have complained about their PC, took it to a shop, plugged it in and GPU is fine, and all because the shop's electricity was not dirty.
So yeah, you have electric/psu/motherboard/cables/case as things to try, but more often than not, its the GPU and your luck, although I find it too odd that 3 GPUs make the same sound. I would have thought there would be some change between 2 msi cards and 1 Asus.
Mines a new ish top tier PSU that worked with the last card 3080 fine, so I'm not worried about cleaning it. Same plug/socket etc.
Sounds like undervolting may be the way to go. Sounds like you only lose a few fps (which would bring it down to the founders edition) ans save power, thermals and noise. That been said definitely going to see if it "wears" in first.
Asus in my experience generally have terrible cards for coil whine, so not overly surprised there.