Originally Posted by SH64
Plus more power draw & heat.
I don't think a performance enthusiast or hardcore gamer will care about power draw, and they'll mitigate the heat as best they can.
There are two crowds here, the ones who care about best bang for the buck, in which case, neither card is very popular, or those that care about pure performance. For those that care about pure performance, the GTX280 wins for a single GPU, and the HD4870 wins for a Crossfire setup, especially on one card.