A few questions about the HD6970

I still have my brother's computer I built for him for about another week and while I've got it I want to do a bit more tweaking to it. In regards to the 6970, whats a safe voltage/temperature to stay under. I downloaded MSI Afterburner and have the card set to 1250mV, 975MHz Core, and 1475MHz memory. The card was stable at those clocks at 1225mV but, for some reason, the small bump in voltage resulted in almost a 100 point increase in the 3dMark11 score to P6187. The temperature under load stays right at about 60C and could be lowered if necessary by changing the fan profile. Are these settings OK for 24/7 operations?

100 points is about within the margin of error.. either that or its was teetering on stability.

If its someone else's computer, I would leave it at stock. 6970 will play anything under the sun with high graphics and AA at 1920x1200 and down.

I will leave it then. In all honesty, I'm just trying to learn everything about all of the components in the system so I can inform him when he makes all of the decisions. I appreciate the insight.