GTX 980M (Alienware) produces polygon artifacts whenever rendering in 3D, but no crashing

[WQXGAisStillGreat]

I'm taking a look at a laptop for a friend and I haven't seen this symptom before... I can launch Unigine Heaven (or pretty much any game) and see visual glitches immediately (polygons appearing sporadically over top the 3D rendering,) but I can run the benchmark or games indefinitely with no actual crashes. I've already performed a 'Clean' install of the driver via GeForce experience, again with DDU in safe mode, and changed the aging thermal paste. No change in behavior after each procedure. GPU temps stay 65-70C when running Heaven. He has Intel onboard graphics as well, but has set the preference to always use the Nvidia GPU. Anything else I can try before resorting to swapping the chip?

 

Thanks!

[WQXGAisStillGreat]

Here's a video of Heaven showing artifacts. Anyone have ideas?