great i'll look at that crossfire mobo, i didnt see anything on the nvidia website about how much bandwidth the 8800s use, all they say is that their x16PCIe but no actually measurements on their site or any others..
1) You wont be able to run SLI on a crossfire board anyway, and all of them give you x16 bandwidth for a single card.
2) There are no Core 2 Duo boards capeable of dual x16 crossfire, only S939 and possibly AM2.
3) All PCIe Gfx cards are x16, barring a small handfull of Matrox ones, but it has been shown that they dont use all this bandwidth. The last example I have seen of such a test was pre-8800 however. I personally think that x8 would have hardly any impact on performance, even on an 8800GTX
4) The 8800GTX will work in x8 mode, if thats what you are asking. I have run multiple monitors in my board with my 8800GTX and my old 7900GT before, and that worked fine. (yes, there are driver conflict issues, you have to use the modded 8800 drivers that support other cards)
i've found my answer with a review at techspot which compares two nforce 680i SLI and 650i SLI mobos with 8800GTXs in SLI... There was no difference in performance, so dual x16 PCIe doesnt matter even with 2 8800s... I'm still curious to know how much bandwidth they actually do use and to know if and when dual x16 PCIe will be necessary to run SLI/Crossfire.