Z97 PCI-E Lanes Question

[Tyerker]

I am of the understanding that this chipset will only support a total of 16 PCI-E Lanes, so SLI would be 8x+8x. No dual 16X SLI.

Assuming I am correct in this understanding, is 8x the next step down from 16x, if other slots use additional lanes?

Here's why I ask... If I were to add-in the following cards
- PCI-E 1x Sound Card
- PCI-E 1x WiFi Card
- PCI-E 2x SSD

This would take up 4 lanes. So then would a single GPU run at 12x? Or would it automatically step down to 8x as soon as I put in any PCI-E add-in card?

 

[EarthDog]

There is no such thing as 12x. It would step down to 8x.

 

[Tyerker]

But 8x for a 780ti powering a 144Hz 1080p monitor is probably still enough bandwidth, right? Potentially even enough for a 980ti @ 4k? That's the main thing, is I want to make sure if I use an add-in card that I won't have any issue with a single-GPU setup for the life of this PC.

 

[EarthDog]

http://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/21.html

 

[Tyerker]

Well then, guess it's a non-issue all around. Thanks for the heads up.

 

[WhitehawkEQ]

I am of the understanding that this chipset will only support a total of 16 PCI-E Lanes, so SLI would be 8x+8x. No dual 16X SLI.

Assuming I am correct in this understanding, is 8x the next step down from 16x, if other slots use additional lanes?

Here's why I ask... If I were to add-in the following cards
- PCI-E 1x Sound Card
- PCI-E 1x WiFi Card
- PCI-E 2x SSD

This would take up 4 lanes. So then would a single GPU run at 12x? Or would it automatically step down to 8x as soon as I put in any PCI-E add-in card?

I could not find a block diagram for your MB, but here is a link to the Intel Z97 chipset block diagram to give you an idea on what is going on.
performance-chipsets/z97-chipset-diagram

The x16 and x8 PCI-E slots goto the NB in the CPU, the other PCI-E slots goto the Z97 chipset.

 

[caddi daddi]

so, with 1 gpu= x16
2 gpu= x8
3 gpu= x4
correct?

 

[ATMINSIDE]

so, with 1 gpu= x16
2 gpu= x8
3 gpu= x4
correct?

This depends on how the motherboard splits it.

 

[Woomack]

It's more like 16+4+4 or 8+8+4+1 ( or whatever left on board ) ... depends from motherboard but usually it looks like this.

In IB/HW, CPU = 16 pcie 3.0 lanes, Z87/97 = 8 pcie 2.0 lanes
In Skylake, CPU = 16 pcie 3.0 lanes, Z170 = 20x pcie 3.0 lanes
Max number of usable pcie lanes depends from motherboard design.

 

[Tyerker]

so, with 1 gpu= x16
2 gpu= x8
3 gpu= x4
correct?

This motherboard only does 2-way SLI at 8x. No 3-way SLI support, they saved that for the Classified model.

As far as the lane structure of the slots, it has 4 fully-pinned and soldered x16 slots, and a single x1. So I'm not sure what they would send where. I'll see if the manual outlines any of that.

 

[EarthDog]

Well, SLI REQUIRES 8x, so that is what the concern is there.

 

[Tyerker]

For the record, I don't foresee running SLI on this build, because the only GPU upgrade I see myself performing with this CPU/Mobo would be something like a 980ti, and I really don't have the money to SLI those. And to SLI the 780ti doesn't really make sense, with the 3GB of RAM.

I think ED's post with the 8x vs 16x performance comparison, and knowing for sure that it jumps straight down from 8x to 16x, was what I needed.

But all of that being said, I am intrigued by the fact that the chipset has separate PCI-E lanes. SLI could still be a possibility, if it comes to that.