PCI express slots 2x16 (x8x8 each?)

[coergo]

Simple question probably,

I'm a little confused about PCI express slots. I want to run three cards: two high end video cards (Thinking GTX570) in an SLi and a wireless N adapter.


I'm looking at the wireless adapter:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833320048

This seems to plug into the PCI Express 1x slot right?

Would I be able to run that + the two sli'ed video cards without hitting a bandwidth bottleneck?

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131701

That motherboard says PCI-Express x16 or 2 at x8. This is where i'm getting confused

 

[rolli59]

Yes for the wifi!
Yes about the bottleneck!
With two cards in the X16 slots the board shares the bandwidth so the would run 8x8 but a single card will run x16 regardless of what you have in the other slots.

 

[coergo]

so that means i need to get a board with two x16 slots then right?

 

[rolli59]

If you want a board for 16x16 SLI then you need something like this http://www.newegg.com/Product/Product.aspx?Item=N82E16813131700
There is really no need to though unless you were going to crossfire or SLI dual GPU cards like HD6990. There would be about 2% max performance hit with 2 x GTX570 on 8x8 vs 16 x16

 

[coergo]

Hey rolli, really appreciate your answers



That board says: "4 x PCIe 2.0 x16 (single @x16, dual @x8, triple @x8, x16, x16 )"

So wouldn't it be the same problem?

You said the 2x570's wont really bennefit that much from dual@16, would it be noticable though?

Also does the x1 wirless nic card feed into that same bottlenecK?

 

[rolli59]

Sorry about that you are right. I was actually looking for the Asus supercomputer version that has the nforce200 chip that allows for 16x16 in SLI. There will not be a noticeable difference but measurable, that is if you get 50fps on 8x8 you would get 51fps on 16x16.
The WIFI will not be an issue in the bottleneck, there are reserved rails for the other slots.