65C is a low temp (especially if you're using air cooling). I run at 80C 24/7.

It will be better to run your card 24/7 at 90C, than working at 80C 12h/day, and 50C the 12 others, all year long. The change in temperature will change the density of components, and that is a bad thing for your hardware. Worst than just keeping it busy at a higher temperature.

130C is a bad idea. I don't like hitting the 90C, but maybe that's just me.

Thanks for the thoughts. I read about that too, and don't know what to think about that yet. Any other insights?

It is in theory possible, but most likely won't happen. Some of the coins are probably already lost forever, since some people probably forgot their wallet password. Also, everybody that owns bitcoins would need to make a transaction with that guy. In the event that someone starts such a quest, while he progresses in getting all the coins (and not spending them) it would make the bitcoins more and more rare, therefore increasing the value of every coin in circulation, which would make it harder for him as time goes by.

I don't see that as a threat.

Got a steady 750mh/s out of a 5970 for a few weeks. I'll be waiting for a few more weeks, and maybe get some more power.

I'm no expert, but I don't like the idea of getting the clock waaayy too high, even if I can keep the temperature low. I like to look at what others used as OC settings, and pick a setting somewhere over the middle range, but not too high either. There's always someone proud about reaching the limits of the card stability and posting it. I believe this one will have troubles in a few weeks/months.