This is good for a start. There's one hour of MSI's Kombustor stability test on a Sapphire HD 6850 @ 945|1150 default voltage. Peak load was 68C. That's not bad for pumping out 600+ FPS for an hour. I used 80% fan speed because I didn't want to get screwed by thermals at like 55mins into the test. Tomorrow I am going to try 56% fan speed and see what happens.
Voltage boosting will come as soon as MSI update Afterburner. In any case, my nephew will be perfectly fine with a card that does 945. Poor kid is on an HD 3850 now