Any update on this? I have the exact same problem pretty much the exact setup, except for a 2600 cpu and a 570 8gb as my gpu. What i ussually do is reconnect the hdmi from the gpu and it usually solves it for a while. However i also encounter this problem while on the desktop or using windowed desktop apps (normal workloads).
For a moment i thought it was a power supply issue, but it shouldn't be a problem since the recommendation is a 350w one, and i own a 500w psu.
Thanks in advance for any update
Found a fix
At least what worked for me was. I disabled the "HDMI link assurance" and HDCP options on settings/display on radeon settings. The HDCP one is located under "overrides"
I haven't encountered the problem since...
Hope this helps.