X99 Gmaing i7 / 6800k

I was hoping someone could tell me what im missing on my setup here.  I can not get PCI-e width to 16x with 1080gtx sli.  I just upgraded from a Asus x99 deluxe with 5820 and 980 gtx in sli and had 16x width.

You mentioned GTX 1080 SLI, I take it you have 2 GTX 1080s? As Parsec noted, make sure you are using the correct slot config.

Go18Go wrote: I was hoping someone could tell me what im missing on my setup here.  I can not get PCI-e width to 16x with 1080gtx sli.  I just upgraded from a Asus x99 deluxe with 5820 and 980 gtx in sli and had 16x width. I changed tot he new setup mostly to get m.2 and i have a bootable 950 pro.  the system works perfect just cant figure out the width reduction.  And it does not change under load, always stays at 8x I know ultimately it doesn't matter but it does matter from a phsyc standpoint when you build a whole new system and go backwards on paper, you know what i mean?  Especially when i think its jkust a simple setting somewhere im missing. Any ideas would be appreaciaioted

Go18Go wrote: The cards are in 2 and 4.  I have no sata drives connected to affect lane speed, and only have a single m.2.

Thanks Xaltar, I missed the SLI configuration!

That explains it, plus you are using an i7-5820K, and an M.2 SSD, in the M2_2 slot.

Your i7-5820K has 28 PCIe 3.0 lanes, not 40 that the higher priced models do. So...

First, dual SLI of x16 + x16 = 32 lanes, impossible with your CPU.

From specifications, which I included in my previous post:

If you install CPU with 28 lanes, PCIE2/PCIE4/PCIE5 will run at x16/x0/x8 or x8/x8/x8

When you put a video card in the PCIE4 slot, with your CPU, then all three slots will run at x8. That is why both cards run at x8.

The best you can do is run one card in PCIE2 at x16, and the other card in PCIE5 at x8. I'm guessing your PC case won't allow you to use a dual slot card in the PCIE5 slot?

Using the M2_2 slot for a PCIe SSD that is configured as PCIe 3.0 x4. The M2_2 slot uses four of the PCIe 3.0 lanes from the CPU. That is how all X99 boards are with M.2 slots that are PCIe 3.0. This makes no difference with a 28 PCIe 3.0 lane CPU.

There is no way you ran both 1080's at PCIe 3.0 x16 on the Asus board with an i7-5820K.

The main limitation here is the i7-5820K, and its 28 PCIe 3.0 lanes.

The specs and math all add up, there's no setting that can change that, sorry to say.

Go18Go wrote: I just upgraded from a Asus x99 deluxe with 5820 and 980 gtx in sli and had 16x width.

i7-5820K also has only 28 lanes.

i7-5930K has 40 lanes

Edit:

Sorry,

i7-4820K has 40 lanes.


Edited by J Z - 17 Oct 2016 at 12:33am