Hm not sure how good miners are when it comes to test the stability of a sytem.
I can recommend some stress test tools:
Super Pi (CPU)
toast (CPU)
FurMark (GPU)
PCMark (whole system benchmark)
Those test stability for common workloads. For mining only the GPU is stressed, and not even all of it, ROPs and TMUs are idling. That's why I asked what miner gave error reports.