How do I know when my mining GPU has been worn out? How do I know for sure when my mining hardware (GPU in particular) has failed?

How can I be certain that my card is at fault and not my software or overclock settings?


  Example: On my rig one of my card's hashrates updates the hash/sec display very slowly and after about 5 minutes of mining phoenix miner will crash and refuse to start up a new instance.


Thanks
You can try running different software for mining after restoring the overclock settings back to factory settings. This way if the graphic card fails, you know the problem exists regardless of the mining software and the overclocking.