People forget there's decade old servers out there working 24/7. Anyway there's a Microsoft research paper on silicon which essentially says that failure rates

People forget there's decade old servers out there working 24/7. Anyway there's a Microsoft research paper on silicon which essentially says that failure rates of CPUs increase by mostly two factors: - cycles. The more calculations the higher the rate of failure - temperature/power. I will let you guess it by yourself. Even minor slips overvoltages and overclocks can enhance failure rates by magnitude of orders. Getting back to your comment: I would've chosen a GPU used for mining (if properly cleaned during its life span, far from a given) over years rather than one used by some kid benchmarking and overclocking any day. Because years of crunching calculations did very little damage in comparison to a kid trying to find the overclock limits for few days. Most mining GPUs were used undervolted and underclocked (especially as Ethereum mining was memory rather than core intensive).