That is a sign the GPU is failing. The R9 models were well known to have models with some issues and you would replace the heatsink compound. I'd do this since that's cheap and there is no warranty.
My PC is four years old. It has Radeon R9 280 as the GPU. Recently it crushes when I play games, the screen would show blue stripes and only reboot can bring the windows back. This doesn't happen when I load the game, it happens within 30 seconds when the game is loaded and when I actually start playing.
The windows memory diagnostic showed no problem with RAM. The driver for the GPU is updated, and the PC would crush with all the games I have. I have cleaned the dust and changed the thermal paste, the temperature for the GPU is usually 60C, it's no more than 80C when the crush happened. I have restored my windows to a point where it definitely works.
I suspect the problem is the RAM within the GPU. Do you guys think I should run some other testing before I purchase a new GPU just in case it's some other problems?
Also, my GPU is out of warranty, is there a cheap way to just fix the memory of the GPU so I don't have to spend money on a new card?