I don't think buying a PSU with the hope of fixing 4090 coil whine is a good idea. I've tested mine with 3 different PSUs, also with a separate PSU just for the GPU, and coil whine was exactly the same in all cases. If the whine actually comes from the PSU, then it would help, but if it's coming from the GPU, I think it's unlikely that the GPU will generate less whine with a different PSU.The same story for me, just received 4090FE, which was lost and found (bought in May) and now it is most loud part of my system, all system watercooled, noticed that then higher FPS - more loud, even on 166FPS (I locked, because have 165Ghz monitor) I hear this weird sound.
Thought maybe need to change PSU...
But if PSU could also be the reason of sound - how do I know which PSU I have to buy as replacement?
I have Super Flower Leadex III 850W Gold
Your PSU is an A-tier high quality unit. The only reason to change it is if you think you don't have enough power, which probably depends on what CPU you're running in combination with that 4090.