Created attachment 135027 [details]
Xorg.0.log

(In reply to Mike Lothian from comment #15)
> Are there any changes when you boot the system with radeon.runpm=0, this
> will mean the card never powers down
> 
> What distro are you running?
> 
> You mention trying older kernel version, did you try older mesa versions too?
> 
> Can you attach your Xorg.0.log too

radeon.runpm=0 doesn't make any change.

I am running Ubuntu 16.04 LTS which using Linux kernel 4.4 and Mesa 11.2.0
before upgrading the system.
After the system upgraded, it uses Mesa 17.0.7 instead.