Considering that it is 17% for the reference fans, the ones most of us are stuck with, seems like the figure I am going to use. And on those fans it is speed as well as dust that are the factors that kill them.
Mine are reference fans as well. All HD5970s are reference designs.
7% isn't 0%. Now if your were on year 5 with 0% failure rate then maybe it proved something.
7% still proves my point as it is significantly inferior
to the 17% of someone who doesn't even run at 100% fan speed. Besides, why would you want to mine with a 5-year old card that consumes 4 times the energy to produce the same amount of work? I expect to upgrade my 5970s after about 2-2.5 years. They are already more than halfway through their service life.
I think you guys also forget that skimping on cooling and running a card 10C hotter will wear out the electronic components faster.