I've never ventured into the territory past overclocking a video card's gpu and vram via software before.
Currently, my 8800 GT's seem to be stable at around 710mhz core. Anything past that artifacts. I played around with increasing the voltage to 1.1v using a bios flash. I was able to reach 760mhz core without errors with some basic testing and benching. My memory is stuck somewhere between 950 - 1000mhz. Haven't found the sweet spot yet.
With the 1.1v and 760 core my temps never passed 44c (Using dual orb, plus there is a 120mm case fan blowing directly onto the cards). Temp wise I know I am fine.
As long as I keep the temps reasonable. Is there much of a risk with the increased voltage and high clock speeds? Is it the same idea as a cpu? A properly overclocked cpu usually only cuts a very short time off of its life span. GPU's on the other hand, I have no expierence with in this respect. If it is going to be a trade off of potentially frying my gpu not too far down the road for an extra 50 mhz increase. I will take the lower clock speeds. But if there is a very small chance, the same with overclocking my E6400. I'll go for the higher speeds