> On the map it only buzzes when I move the cursor, interestingly enough

Sounds like the game is doing more when the cursor moves around, they're probably checking for where the cursor is, and something is making the CPU/GPU do a bunch of extra work, which finally triggers the coil whine when the PSU is more heavily used.

I've basically had the same issue with Nvidia cards since the 2080ti started doing coil whine as soon as I opened Unreal Engine. Some programs trigger different sounds, depending on how much/well they use the GPU, and I've had the literal same experience with "hovering with my mouse over element X triggers coil whine" multiple times before.