As the above poster said this is probably coil whine. You can verify this by increasing fan speed when the GPU is at idle with something like msi afterbuner, if it doesn't buzz its not the fans.
Many GPU's will produce coil whine under certain loads and when at certain framerates, with my card the higher the framerate the louder the whine tends to get.
I also doubt this has anything to do with the stuttering.
To diagnose he stuttering i need more info. Specs, GPU and CPU load in game with vsync off, are you using the latest GPU drivers, and CPU and GPU temps under load in game would be a start.