like he said, its stable till ur temps are getting close to 80*C and when u get artifacts in games or run a synthetic tester for artifacts
my 9800GT wont clock that high, lol. i lost stability at 750 core. i dont think im gonna play with voltages, the card does anything i want, i just OCed it for fun. my temps are not bad since i have the akimbo dual slot cooler and i crank the fan to 100% sometimes. its at 80% normally