Has anyone actually gotten an Nvidia card to mine efficiently enough to pay for it's own power consumption? Or are these solely for people mining with "free" electricity?
I think the short answer is
no. I don`t think anyone bought an nvidia card just for mining. I think (just like me) we got nv card because other reasons (for me, I use it for work). In the computer spare time, mining can run, but it`s not worth unless you have "free" electricity.
In my particular case, I had an ATI HD 5770 but it sucked at flightsimming (which is what I built my computer for) so I sold that (stupid, I know, but I really didn't know much about bitcoins then) and bought the 670 I'm now using. It runs FSX great, but now I got interested in bitcoins and found out that the card I sold can hash at least twice as much than what the 670 can do normally. I can't really undo the sale, and buying an ATI card that can mine efficiently is more or less out of the question right now.
Hence, my interest in optimizing my card's performance. I also know that GPU mining is almost dead, but it's worth a shot, I guess.