Question about PCIE Lanes (M.2 + PCIE SSD)

OnionKing

Commendable
Jul 25, 2016
40
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1,565
I am a bit confused, lets say i have two scenarios (Note, neither system will have a motherboard featuring PLX chips)

System 1) Z170 platform (i7 6700k) A GTX 1080, there is a Samsung 950 EVO M.2 SSD attached to the mobo, along with a PCIE SSD in a PCIE slot, an Intel 750 1.2TB SSD

System 2) X99 platform (i7 6950x) A GTX 1080, there is a Samsung 950 EVO in the M.2 port, and an Intel 750 PCIE 1.2TB SSD

1) I know that the M.2 SSD gets its lanes from the chipset, would the Intel 750 run in x8, and the GTX 1080 run in x8 on the Z170 platform due to the total of 16 pcie lanes from the CPU?

2) Would the GPU run at x16, and the pcie SSD run at x8 (max speed) on X99 due to the 40 pcie lanes provided by the CPU?

3) Would it be possible to run SLI GPUs on the Z170 platform if the PCIE SSD is in use?

4) Would it be viable to go with X99 if youd want to run a GPU at full speed, have a M.2 and PCIE SSD, with the ability to SLI (or XFire) in the future?

 
Solution
1) This is correct.

2) Depends on the CPU, i think many only had 28? But yes, you're correct.

3) x8/x4/x4 it would run, but it would suffer a hit in performance.

4) Yeah it would. But it would be equally viable and significantly cheaper to do away with the PCIE SSD and just use the m.2 or traditional drives which, on skylake, are on the same Z170 PCIE I/O bus anyway.
1) This is correct.

2) Depends on the CPU, i think many only had 28? But yes, you're correct.

3) x8/x4/x4 it would run, but it would suffer a hit in performance.

4) Yeah it would. But it would be equally viable and significantly cheaper to do away with the PCIE SSD and just use the m.2 or traditional drives which, on skylake, are on the same Z170 PCIE I/O bus anyway.
 
Solution


16x -4x = 12x
Crossfire needs
8x + 8x = 16x
12x < 16x
Therefore,
You can't do proper crossfire with Intel pcie 4x SSD installed in a skylake system.
 


Not true. Please stop posting misinformation without sources on already answered questions.

To explain further...

Pcie lanes on z170 are for I/O only, not the pcie slots themselves. The z170s lanes are already accounted for with SATA m.2, etc.

CPU pcie lanes are limited to 16 on all LGA 1151 CPUs.

You can use a single GPU and a PCIE SSD.
Or you can use crossfired GPUs.
But you can't have both crossfire and a pcie SSD.

If you want all that you need 2011-v3, there is no question or argument, just fact.
 

tom_spinach

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Jul 26, 2015
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I am not sure about your question, you said "there is a Samsung 950 EVO in the M.2 port, and an Intel 750 PCIE 1.2TB SSD", so there is m.2 and Intel 750 SSD and if you want to do SLI you can run 2x GPU at 16 and either the Intel 750 SSD OR the M.2 SSD, both might not work. MIght depend on Motherboard.
 

jonathan110721

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Nov 10, 2011
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18,510


Correct me if I'm wrong but his answer to number 3 doesn't work. I thought nvidia sli requires 8x/8x minimum

So if a pci-e ssd is plugged in and two GTX 1080s are also plugged in, sli will be impossible!