Can you perform a stress test using OCCT and share screen shots ?
post #4 - could you redo and select "+12V" (third image) this time ?
Coil whine doesn't prove anything - other that there is a coil somewhere that when under certain condition when there is a mechanical resonance that make the winding vibrates within audible frequencies. Or it may be due to bad design of the pcb if under some circumstances, the coil actually overloads.
Also - you probably wouldn't be able to locate the exact position of the coil in question.
Ok - back to your images. It indicates PSU are ok. The images of fan speeds are of no interest because it all depend on the setup/configuration of the fan controller (doesn't matter if hw or software).
Actually, I'm more into failure of motherboard or GPU.
Try to uninstall current GPU driver, and install an older version - just to see if that fix the issue.
Also, there are some people suggesting the software Catzilla does a more realistic stress test of GPU. You can try that too (both with current and older driver) - to see if it runs successfully.