crossfire at x8 -- performance hit?

[HowlingBlue]

I'm doing an upgrade right now on my computer, and am upgrading to Gigabyte's GA-X58A-UD5, since it best fit what I was looking for in a mobo. However, I have one concern. I'm running a 5970 with an 8800GT for physX right now, and was thinking about getting a second 5970 later for crossfire.

However, unless I get rid of the 8800GT, the speed of the second 5970 will be at X8. Out of curiosity, if I decided to keep both, how big of a performance hit would I receive when I crossfired them?

(As a note, I am aware that 5970 crossfire is still not working well in the drivers, but hopefully by the time I can consider getting one, that will be fixed.)

Thanks!

[Gilly]

I don't think the lack of bandwidth would make much difference. Remembering back from the 965/975 chipsets, where you had 2x 8 or 2x 16 ports on 975 (I don't remember) or 16x on 1 and 4x on the 2nd, the difference in performance wasn't too much, unless the res was really high, with high levels of AA.

Although, these cards being so powerful, I don't know if they are more bandwidth hungry than the high end cards of that era.

[Yui]

Why even bother buying a second 5970? What games do you play and what settings are not maxed out when using a single 5970? Also, why spend all these money just to play games?

Just get rid of your physics card if you ever buy the second 5970. Probably the games you play don't really need physx.