Anyhow, fans will only last so many cycles -- they don't age like a human being. Their only "aging" is how many times the fan has spun around. More RPM = less life, it's that simple.
I wouldn't pay more than 40% of original price for a card that was "run to death".
2 XFX
2 Sapph
They don't need more than 60% fan speed, that's at 1ghz/1.225v.
All cards are running 65-70°c in 2 different boxes.
And I 100% agree with PcChip, 1 Sapph fan went bad in the first month, smooth sailing since.
Did you check your VRM temps on those cards? because my Asus reference 5850 runs at 1020 mhz, 300 mem, 1.2v and with 50% fan the VRM gets up to 140 degrees wich is 10 degrees above max supported operating temp of the chips according to the datasheet...
Of course, top cards mid 70°c, bottom cards are mid 60°c.
The 5850 probably has an inferior design, IDK for sure.
Does it have the heat pipe on the base plate for the vregs?