Coil whine that only occurs at high FPS is 100% attributable to the card itself and not the PSU. You can quickly notice if this is the case during load sequences. When the whine is gone during loading and pops up when in-game, for example.
When in doubt, use a toilet roll and stick it to your ear, point at each component under load and you will have the answer soon enough. Another dead giveaway is firing up a different game that stays around 60-70 FPS under a 100% GPU load. If the coil whine doesn't appear in that game, you know this is purely FPS related and therefore a GPU whine.
The fix was already presented. If you don't like Vsync but also don't like screen tear, use an FPS cap above monitor refresh (ie 140-150 for a 120 hz monitor is a good setting) and combine it with Fast Sync, and/or cap FPS to a point where you lose the whine. Running entirely uncapped FPS is very 2013 anyways, no point in doing it these days, not even for latency.
Or take the expensive route and keep replacing components until its gone, but that may never happen
FYI have it too on my MSI Gaming X 1080, exclusively at very high FPS, as do most people regardless of brand choice.
If a card also whines under average loads and at lower FPS, then I would certainly RMA, but otherwise, no.
