just received mine, pretty poor overclockers.
3.6ns hynix chips, but without heatsink on the ram, it gets pretty hot. 270/541(250/514 default) was all i can.
ran a couple of 3dmarks, but i don't think it'll even be stable at that in the long run.
cards are used/pulls as the gold contacts show fair amount of wear.
a decent deal, but not hot imho. I got 12323 3dmarks at default, probably 1000-1200 more if it was really 600mhz.
New retail one would be new, cables, box, software, maybe a longer warranty for only $20-30 more, so instead of hot deal, its pretty much you get what you paid for deal.
Edit: Looks like I can only get to 275/522 mhz before artifacts shows up. Saddened by the poor ocing results of my card
Edit: the speed should be stamped on the memory chip itself. Usually the last 2 numbers after a "-" symbol