Nvidia cards can't have the firmware flashed, so the only thing you need to look for are do the fans work and how is the heat underload. You will find that hard core gamer are harder on cards than miners since miners underclock and try to find the best performance/power ratio vs overclocking.
PassMark or 3Dmark for benching
https://www.3dmark.com/
https://www.videocardbenchmark.net/
HWmonitor for heat and voltage
https://www.cpuid.com/softwares/hwmonitor.html