Well overclocking it gives you a free performance boost and most people don't keep a card 5 years or how ever long the service life could be, because by then it'd be way obsolete.

As for it causeing premature death if it's cooled adequately it shouldn't hurt it after all they are rated for something like 120 degree's celsius however at that temperature it'd start to die fast.

Well from what I've read so far...alot been keeping up on every ATI and Nvidia card thread. Putting it upto 35% fan speed or so is still pretty silent yet cools it to below 60 degrees celcius at load