crossfire 8x8 vs 16x16

http://www.tomshardware.com/reviews/pci-express-2-0,191...
if your doing crossfire i would get a x48

If you're getting a pair of HD 4850 or HD 4870 or HD 4870x2 I suggest you get an X48, if you can. For HD 3870 or lower, P45 will be fine, IMO.

I haven't seen any reviews but you have to remember that 8x PCI-E 2.0 is the same as 16x PCI-E so the P45 still has a lot of bandwidth available. I remember seeing a Tom's article a while back where only the very fastest cards (8800GTX and Ultra at the time) saw any difference in performance between PCI-E 8x and 16x so with PCI-E 2.0 8x being the equivalent of PCI-E 16x I would imagine that anything but the X2 cards would not see a difference. With that said though if you plan on keeping the system for a while and just upgrading the video card you might want the added headroom of PCI-E 2.0 16x

So essentially what your saying is that any card that isn't bottlenecked at PCI-E 1.1 in a single card is not going to be bottlenecked in a 8x8 PCI-E 2.0 setup. As from what I've heard, not many cards really push the PCI-E 1.1 bandwith atm. The best card I'm willing to buy at the moment is a 4850, will that hit the PCI-E 1.1 limit?

That is what I'm saying and I haven't seen the benchmarks but i would say that the 4850 wouldn't be close to filling the PCI-E 2.0 8x bandwidth.

If your only looking for the 4850 why are you worried about that? Most p45's are 16x with one card and either 16x and 4x or 8x and 8x with 2 cards so if you are only getting 1 card you will still have 16x.

well two 8800GT's in sli on the x8 x8 evga 750i ftw is no difference in performance compared to the same setup on a 780i/790i.

I have two 4870s on the P45 and although its only x8 link the fact its PCIe 2.0 should have enough bandwidth, but I do get the feeling I'm underperfoming. I regret not getting a x16 link mobo now.

look http://www.tomshardware.com/reviews/pci-express-2-0,191...
http://www.tomshardware.com/reviews/pci-express-2-0,191...

Thanks, you know I remembered them doing something like that but I thought it was with PCI-E not PCI-E 2.0. Even with the 3850 there was a difference at high resolutions so the X38 or X48 would be the best choice if looking to use more than 1 video card.