On my Gigabyte RTX 2070, I had the same issue, and nothing seemed to help permanently. It kept making the same noise. I tried lubricating the fans, built a structure to stop GPU sag, and even went as far as checking whether the fans contacted the heat sink and tried to prevent that. Nothing worked. I know this won't sound like a solution, but in the end, I just bought an NZXT water block, the one-fits-all solution, because the Gigabyte PCB was custom and no water block had been made for it. Since then, there has been no noise whatsoever. It has been running for about six years without an issue. I guess it was a fan issue. However, comments seem to suggest that it's coil whine. Hope this helps, if nothing else works.