Try capping FPS in driver and also make sure you are not undervolting the GPU. This can also cause coil whine. Very High FPS, as well as undervolting will have an effect.
If that is not the case, then it may be related to the issue that I keep bringing up about the aggressive power saving that AMD implemented in the latest drivers.
This may also cause coil whine, as the voltage drops a lot. It also causes driver timeouts.