7850 vs 7870 if both overclocked?

twelve25

Distinguished
I am hearing a lot about how the 7850 has a ton of OC headroom. I've heard it said you can OC a 7850 to perform like a 7870. But if you are willing to OC the 7850, wouldn't you also try to OC the 7870? So assuming you do a conservative, realistically possible overclock of both cards, how does the gap of performance look?