Using the editor I have found that my graphics card begins to whine (a high pitched squeeling noise, also known as coil whine).
This is due to the GPU generating a huge amount of frames. This causes the GPU to heat up to around 80 degrees celcius.
The issue is especially prominent when I zoom fully to a unit on the editor.
If I enable VSync the coil whine will stop, and the graphics card will sit at around 40 degrees.
Disable VSync, run editor
GPU - ATi Radeon r9 280x 3GB (XFX) (latest drivers)
CPU - Intel Core i5-4440 @ 3.10GHz
Arma 3 - no mods
Coil whining happens when the videocard produces a high amound of frames per second. This is especially noticeable in the 2D editor, since your card has nothing hard to do.
VSYNC's job is it, to limit the FPS to either 30,60 or 120 FPS, to reduce power consumption, coil whining and heat output.
Therefore, what you've reported is absolutely normal. Just keep VSYNC on, or limit your FPS with an external program like MSI Afterburning.
kind regards
Edit: You can also try to search your AMD driver for "adaptive VSYNC". However, I'm not sure if that is an Nvidia only technology.
Information:
http://www.geforce.com/hardware/technology/adaptive-vsync/technology
R3vo