5970 review.

[foothead]

I really don't think it's going to bother you as much as you think. It's about the same difference for x8 and x16 as it is for PCI-E 1.1 vs 2.0. 6-7 frames mostly. I think you'll see more of a benefit from offloading the CPU than you will see a loss from losing bandwidth.

PCI-E Scaling.

This is where you begin to see options. Run your 4870x2 at 16 lanes and tape down the PhysX card to 4 lanes.

ehhh IDK, the issue I have isn't x8, it's the fact that the x8 bandwidth would be shared between 2 gpu's, so I'm not really sure how it'll perform. I have to buy a new mobo either way, and the DFI has the most features I want,the issue is that in reviews I've read, they can't get the reference clock over like 275, which isnt an issue most of the time for me, but I'm going to be attempting dry ice cooling at some point, so it won't be too good there.

 

[Teny]

lol ok. I'm actually debating getting a lower-end nvidia card for physx, but I'm kinda worried that the x8/x8 bandwidth drop will kill it.

That's why I bought an mobo that supported x16/x16, but it's not PCI-E 2.0 unfortunately, but I still get the same speed when gaming in PCI-1.1 vs PCI-E 2.0.
I got an SLI mobo so I can SLI my 8800GT, but there aren't many games that supports SLI and it doesn't even seem worth it to SLI 8800GT's anymore.