Originally Posted by IHateDells
Will the two card running at 8X each perform better than just a single card running at 16x?
Assuming all 3 cards are the same card yes (i.e. 2x 4870s running at 8X will perform better than 1x 4870 running at 16X), however if you're gonna lower the card just to get crossfire, i wouldn't recommend it.
1x 5870 will stomp 2x 4870s, no matter what they are running at.