[Povell42]

Is it always or when the GPU is under load? (or get louder under load.)
It might be coil whine impacting audio. Try putting some Ferrite Cores on the PCI-E cables were they are connected to the 1080.
they are cheap to try: https://www.amazon.com/gp/product/B01E5E5IY4/

This is a overclocker trick when a power or volt mod (of the GPU) causes noise going out via HDMI.
One of my 3090s has this problem and the cores helped a ton... i still might replace it if there is every stock. ugh.

i used to use them on my 1080s
(very old timespy pix)

Thanks for the option. I believe the noise is only there when the PC is on. It gets louder, and dynamic, with any graphic movement on screen. For instance just moving a window around on the desktop will cause the noise to crackle and hum louder.

 

[jiiteepee]

Thanks for the option. I believe the noise is only there when the PC is on. It gets louder, and dynamic, with any graphic movement on screen. For instance just moving a window around on the desktop will cause the noise to crackle and hum louder.

On older PC's this type of issue was caused by either shared IRQ or hardware acceleration (audio, graphics) or mouse trapping sampling rate?

IRQ sharing should not be an issue today but, have you tried decrease mouse rate and disable HW accelerations?

 

[Zurv]

older PC? it didn't tell you his PC but only the video card - it is likely a pretty modern system (as nothing major has changed in PCs for ~10 yers). IRQs don't really matter anymore.
It is very very likely that is is coil whine from the video card. the ferrite beads will help. Some care just do this.. which kinda sucks.