i've had a weird experience with mine though, my super overclock 6870 overclocks better on their "overclock" edition bios, then it does with their "super overclock" bios even with their utility (which dosent work that well)
I am getting a 7850 and I know the 7870 is not worth buying over it but can the 7850 overclock to 7870 levels??
I am getting a factory overclocked msi is that already at 7870 levels?
my MSI 7870 GHz Edition is running 1200\1350 1230v through Afterburner and stays in the high 50°s when high-end gaming. for slightly older games like Bad Company 2 I run it downclocked to 950\1150 and they all run great, temps stay in the 40°s.
Haha dude theres so many safety exceptions written into video card drivers its almost impossible to kill your card with stock drivers. Overclocked chips won't last as long as stock but chances are you'll be upgrading to a newer card before this happens anyways. But to answer your question overclocking really depends on the type of cooling your using, I have a factory overclocked card and it will hit 150 + clock offset at the highest voltage on water and run 3dmark 11 extreme settings, 75 max on air just put an extra fan over back of the card and an exhaust fan underneath if your doing it on air. No body can tell you if it would be better than a stock 7870 you would have to benchmark your card and compare.