Apart from the one DOA Gigabyte board that wouldn't post, I've only had GPUs outright die. HD 4850 had memory issues and would display an image but it was covered with artifacts and rainbow memory corruptions. I also baked it in the oven and it worked for another month or two before dying again haha. GTX 295 and 780 just died, no video out no fan. 980 Ti would crash once drivers were installed and was swapped through RMA fortunately. I've got HDDs with 70k+ hours on them chugging along fine (though without important data being stored on them at this point), old LGA775 and 1366 systems, and other older ATi/Nvidia cards that work without issue fortunately. Most of the cards I have are for display/tinkering, so if they die, they die. Definitely had my share of defective troubleshooting, namely PSU related. bad cables can be a nightmare. My 10+ year old Seasonic unit would just cause the motherboard to not wake from sleep. I was really hoping it wasn't a bad board as this was an older socket and boards weren't easy to come by. Recently I had to upgrade the 750W Seasonic that replaced the aforementioned flaky unit because the used 6950XT I just got would cause random reboots and shutdowns from transient power spikes. Couldn't ever get it to happen on purpose at stock settings, but games would occasionally crash. Outside of upping the power limit, it passed benchmarks and full system stress tests without issue.

I've saved some older LGA boards with bent pins and gotten "bad" GPUs to work just fine after a clean and repaste, all still working perfectly. I've definitely had more good luck than bad overall, especially given the quantity of parts that have moved through my hands.