I don't think anyone is really interested in running four video cards. It wouldn't make much sense unless your doing video conferencing from a board table and the furthest monitor is 20ft away or you have more than 32 clients connected in a video conference.
I have gathered as an assumption from some early Jan. board specs and the latest early release board, that the board will support these PCI-E 16X slot configurations 8X-16X-1X-16X, 8x-16x-8x-8x and 8X-8X-8X-8X.
There is some spectulation of the first option as it has been printed as 1X-16X-1X-16X I've also seen 8X-16X -__-16X where one of the slots is useless. I'm not sure if the extra 8x would fail leave enough expresslanes from the 46 offered by the 680i chipset for MSI's implementation of Sata, eSata and the one and only 1X slot on the board. My best guess would be is you can use it as any of the options listed. I do have hands-on experience with four slot PCi-e 16x boards and this makes sense to me in my findings, but if the sata, esata and the 1X slot use more than 6 expresslanes it will not be possible to use 2-16X cards along with an 8x card or 2-4X cards. If anyone knows for sure please add info. I can't see MSI deniing us dual 16X SLi and support for another 8X card with two 16x slots left to use. Its really just a matter of MSI leaving enough express lanes and some colorful switching options weather it be in the bios automatic or on the board.
This brings me to another question will the boards support dual 16X SLi and dual hardware raid 4X cards in a 4X-16X-4X-16X configuration for a card like this.
http://www.highpoint-tech.com/USA/rr2310.htm or
http://www.highpoint-tech.com/USA/rr2320.htm
I really don't know much about Physics cards so my question would be will they be 4X or 8X? Or are they going to stay PCI only? If the above configuration does work and the cards are 4X then you could run an 8 channel hardware raid card and a physics card or two different types of physics cards or two hardware raid cards, while running dual 16X SLi.
Why does it always seem no matter what there is never plenty to go around?