There is a certain software in AMD driver that manages power (ACP Application)
Removing it solves the issue. (not having has no impact, this app is for saving power - turning off gpu when not used)

To remove it go to your Programs&Features / Uninstall/Change Programs select your amd catalyst install manager and press change. Then in uninstaller select uninstall manager and select custom. This will allow you to simply remove one of the amd driver features. Select ACP Application and remove it. (This will not uninstall your drivers.)


Regards.