You can overclock the one that is overclocked. The one you are going to buy the evga ACS3? great choice man.
I'm thinking of trading it in for my 7950 gx2.
But still don't know yet......
I think that the one that is overclocked is the manufactured speed w/ warrenty can't bet that. also evga has great return policy. 60 days
If your not saticfied trade it in.