Check for hardware damage (GPU)

I need to check for damage to my graphics card. I suspect I have done damage to my gpu through overclocking. Now, whenever I do anything graphically intensive my screen will flash various colours and then turn off. The system is also then unresponsive.

Here you can find the Dmesg and Xorg logs after such an event.

My question is, what should I be looking for in the system logs to confirm this? Also are there other tools that can give me more diagnostic information about the hardware?