I would guess the clock speed is too high and/or your voltage is too low.
If you are worried about the life of your card, you should lower the clock speed a little. (rather than increase voltage to stabilize the current clock speed.)
When you test your card, keep an eye on the temps. If it gets so hot that you think it will shorten its life span, you should take steps to make it run cooler. You could change the fan profile, lower the clock speed, lower the voltage, or all of the above.
I would also keep the memory at stock speed to help keep things stable.
well i guess the real question is then, is 80C while bench marking unhealthy?