crossfiring question

how much of a performance boost would i get if i crossfired my hd4870 512mb with a hd4870 1 gb on a p45 board? I have a 1920 x 1200 resolution monitor btw.

big time increase, I went up 20 frames in crysis wars online. but you should get a 4890 if going with a 1 gig card because the card is worth the price. If though youare definetly getting the 4870 get the 512mb version because that is what you already have and the system can only use the vram of the lesser card. If you do go with the 4890 use that as your primary card it will be even more of an increase.