It sounds like it could be a driver issue, please provide a report and screenshots here.
If the issue does not occur on older drivers, such as Catalyst 15.11.1 Beta or Catalyst 15.7.1 then i doubt the graphics card is faulty.
Have the Catalyst 15.11.1 beta installed right now, will try rolling back to 15.7.1. It's hard for me to capture a screenshot because it happens and goes away so fast, I will try to capture it on video and take a still from that. Thanks for the response, will update soon.
EDIT: This may not help you. I just noticed you'd already forced the clocks without a positive result.
This sounds like what is referred to the "screen tearing" issue with underclocked 280x cards.
With catalyst drivers, enable Overdrive and create a new "profile" and edit its XML file at C:\Users\USER\AppData\Local\ATI\ACE\Profiles\*.xml
Find: <Feature name="CoreClockTarget
Change next line: <Property name="Want_0" value="30000" /> to <Property name="Want_0" value="50100" />
Find: <Feature name="MemoryClockTarget
Change next line: <Property name="Want_0" value="15000" /> to <Property name="Want_0" value="30000" />
This will increase the minimum GPU/MEM clocks. These are the actual values used in my smurfy.xml profile, and have made my 280x go from crashing within 5 minutes of starting a youtube video to rock-solid stable. The actual reported clocks from Afterburner do not match quite what I put in the XML (seeing 501/700), but since it's rock solid stable I don't much care to tweak further to force that 300MHz memory clock.
Unfortunately you will be stuck with Catalyst, as Crimson's AMD Settings does not offer this functionality at this time and no solution has been reached. You can run the new drivers with Catalyst by just installing the minimal driver on top of your Catalyst installation.
Thanks, I was still having problems so we'll see if this works!
Saved the .xml file and it was automatically rewritten.
The problem still occurs after forcing the minimum clock speeds.