Eh, I think probably the most important difference was that the HD4870 wasn't the fastest card out there. That was the GTX 280. It had to compete with GTX 260, and AMD priced it aggressively to gain market share (and of course promptly nvidia lowered prices and introduced faster GTX 260). That's not the case now, noone really expects any competitive products from nvidia for some months, with even the 5850 beating a GTX 285 (at a currently very similar price point I might add - of course noone has ever argued GTX 285 is good value compared against even the GTX 275). If you compare to dual gpu cards those rv870 cards also seem priced quite competitively.