This seems to currently only occur whilst playing war thunder.
The screen (both of them) will go black, the system will effectively crash, whilst it remains on, the VGA debug LED on my motherboard comes on, and i have to reset the PC.
Powercolor PCS R9 380 4GB
RYZEN 7 1700
Aorus Gaming K5
XFX TS 750
I've run some of my own tests using furmark, stressing the GPU (and CPU at the same time) with a +20% power limit, temps maxed out at 94C, was running for a good 20 minutes, no issues.
12V rail is stable.
Right now, i'm completely lost as to what the problem might be, it just happens completely randomly, weather or not the GPU is under heavy load, and its occurring more frequently (3 times now, the time between the last 2 times was much less than that between the first 2 times)