If these cards were run in proper systems, they would be fine.
The concern is that mining rigs are literally made by stuffing 64 AMD cards on risers in a filing cabinet with minimal airflow, running at 100% usage and 90+ Celcius for months on end.
The high heat for extended periods of time will degrade silicon, which is why manufacturers may refuse to RMA cards if they find issues related to mining[0].
The short of it is the probability of a used mining card failing is much higher than a used card from a regular gaming system.
The concern is that mining rigs are literally made by stuffing 64 AMD cards on risers in a filing cabinet with minimal airflow, running at 100% usage and 90+ Celcius for months on end.
The high heat for extended periods of time will degrade silicon, which is why manufacturers may refuse to RMA cards if they find issues related to mining[0].
The short of it is the probability of a used mining card failing is much higher than a used card from a regular gaming system.
[0]:https://www.pcgamer.com/cryptocurrency-mining-may-void-warra...