Has anyone actually killed a card on here through software overclocking?
Well, I had a 9800 Pro that I heavily overclocked like mad, the ram was even beginning to artifact in 3D mark 03 because I were setting it to high.
.......
It died after about 3+ years (only had a 12 month warranty anyway, OEM card)
I used it for about 18 months, and then passed it onto my brother. It had a custom cooler on it too but it died on him a long time later, so I got him an Nvidia 6200 as a replacement (he doesnt play games, and he is still using that card today

). The ATI 7800 range was already out for a while when it died, but he didnt even need a 7200 and the 6200 was the cheapest thing I could find. The thing is though, he was running it completely at stock settings, and he told me that it was fine for some time, but then the ram started dying.
I still have the thing, lookie:
That was the first card I began modifying after the 12 months warranty ran out (just custom cooler on that one, then also on the X1900, then I chose to look for pre custom cooled cards, 5770s being the exception).
I pretty much thought that if a card does die within 3 years from software overclocking, its a naff card. Temperature is what will kill it fast, like the 120ish degrees 4870 crossfire. I think that if you make sure to keep any current card below 90 degrees, they will be completely fine (GTX 480 is even fine in the 90s).
After they go past 100+, they begin to reach failure level.
The only reason why I didnt sell the 9800 was because I still hadnt ever used Ebay. It was from my cards after that one that I became an Ebay + upgrade slave

.
my Nvidia 6800s, ATI X1900, 3850s, 4850s, 5770s all had no problems at all when overclocked to their max stable levels. The 5770s were the first ones I started bios modding on, just to remove the max OC limit, but that can be done in software now using Afterburner, no more need to bios flash.
Im keeping my current MSIs as they are unmodded, except for the VRM heatsinks I stuck on. They are perfect, great cooler, decent overclocks, and I emailed MSI support asking if they plan on releasing an official bios that allows more voltage

.
I dont want to use the unofficial unlocked ones for these cards since the warranty covers voltage tweaking + overclocking.
The MSI UK warranty is two years from manufacture date, and registration isnt required. Not as good as Asus / Gigabyte who offer 3 years but I dont even keep any cards for that long anyway.