Can someone explain CPU lanes for motherboards?

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GetOwnedGaming

GetOwnedGaming

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Jan 20, 2014
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That is my question, what are they, and how do they affect adding multiple GPU's and Overclocks? I was going to get that AsRock Fatil1ty x99 killer, but then watched JayzTwoCents review, and he said the i7 5820k was limited by that board to 2 GPUs because of CPU lanes. I am now getting the Asus Rampage V Extreme. Will the Rampage V have problems with the lanes of the 5820k? On the Asus website, it said it have 28 and 40 lanes. I have no idea what this means. Sorry for not having a very clear question.


My Build: http://pcpartpicker.com/user/GetOwnedGaming/saved/898xFT


Thanks

Luke

P.S. Who is LOVING the new PCpartpicker format? It is amazing if you ask me <3
 
Solution
Damn_Rookie

That link is to the Maximus V Extreme, which is indeed a 1150 board, and not the Rampage V Extreme mentioned by the OP. ASUS do have a fondness for convoluted naming schemes :)

As mentioned above, the 5820K is certainly capable of 3-way SLI, but that's just one part of the equation; the motherboard also needs to support it as well. It's down to the motherboard manufacturer how they choose to wire up the lanes coming from the CPU. Unlike the ASRock Fatal1ty X99X Killer that doesn't support 3-way SLI with a 5820K, the Rampage V...
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theres no such thing as "CPU Lanes". what he was talking about is PCIe 3.0 lanes - the bus which you connect expansion cards (GPUs, sound cards, raid cards, ect.) to. every CPU has a set amount of PCIe lanes. the 5820k has 28 lanes - enough for 3 nvidia GPUs in SLI. what Jay was talking about in the video, is that the motherboard is optimised for the 5930k and the 5960x, since they have 40 lanes, so the 28 lane 5820k wont be able to use its full potential.

btw i dont like the new PCPartPicker layout. i'm not used to it yet.
 
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Not CPU lanes, but PCIe lanes. How many you have depends on the board and CPU. The 5820K has the same number of PCIe lanes, but if the board doesn't have them wired to the right slots, then some might not get used.

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157540

3 x PCI Express 3.0 x16 Slots (PCIE1 @ x16 mode; PCIE3 @ x16 mode; PCIE5 @ x8 mode)
*If you install CPU with 28 lanes, PCIE1/PCIE3/PCIE4 will work at x16/x8/x4 and 3-Way SLI is not supported. To support 3-Way SLI, please install CPU with 40 lanes.
Click to expand...

So many lanes does the 5820k have?

http://www.tomshardware.com/news/haswell-e-i7-5820k-pci-express,27507.html

Both the Core i7-5960X and the Core i7-5930K will be able to address 40 PCI-Express lanes, but the cheapest Core i7-5820K will only have access to 28 lanes.
Click to expand...

To use EITHER board you'd need to use the 5930K if you want to use Tri SLI.
 
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thats fine, just remember that the 4790k supports only 2-way SLI. if you want 3-way as an option for the future, then you can still go for the 5820k, and a MoBo that supports 3-way SLI with the 5820k
 
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Well, I am learning a lot of new things today. If I were to go with the 5930k and Asus Rampage V Extreme, I COULD go 4 way SLI?
 
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yes, but that would cost much more. also, you dont need the expensive RoG MoBo for 4-way SLI. this (http://uk.pcpartpicker.com/part/gigabyte-motherboard-gax99gaming5) would also give you 4-way SLI support, while keeping the red/black theme, AND costing more then half the price.
 
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3 x PCI Express 3.0 x16 Slots (PCIE1 @ x16 mode; PCIE3 @ x16 mode; PCIE5 @ x8 mode)
*If you install CPU with 28 lanes, PCIE1/PCIE3/PCIE4 will work at x16/x8/x4 and 3-Way SLI is not supported. To support 3-Way SLI, please install CPU with 40 lanes.
Click to expand...

That's what the first board says. If the 5820 has only 28lanes, then it can't do 3 way SLI. (SLI won't work on a 4x PCIe slot.) I read that as the 5820K can't do 3 way SLI.
 
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it can run 3-way SLI if all cards are running in 8x. 2-way will work in any MoBo, but for 3-way it will need a PLX chip.
 
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That link is to the Maximus V Extreme, which is indeed a 1150 board, and not the Rampage V Extreme mentioned by the OP. ASUS do have a fondness for convoluted naming schemes :)

As mentioned above, the 5820K is certainly capable of 3-way SLI, but that's just one part of the equation; the motherboard also needs to support it as well. It's down to the motherboard manufacturer how they choose to wire up the lanes coming from the CPU. Unlike the ASRock Fatal1ty X99X Killer that doesn't support 3-way SLI with a 5820K, the Rampage V Extreme does indeed support 3-way SLI with the 5820K, with the expansion slots running at x8/x8/x8.

GetOwnedGaming: To answer your question, yes, the 5930K has 40 PCIe lanes. Combined with the Rampage V Extreme you can do 4-way SLI with that CPU. If you'd prefer to stick with the 5820K and that same motherboard, you can get up to 3-way SLI.
 
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Solution


Each of the LGA-2011 CPUs has 3 PCie root ports. Two are 16 lanes wide, and one is 8 lanes wide.

Each of the 16 lane ports can be divided into four smaller 4 lane ports, and the 8 lane port can be divided into two 4 lane ports.

Since the CPUs use a PCI bus internally, each of the PCIe root ports is actually a logical PCI-to-PCI bridge. This allows a 40 lane CPU to expose up to 10 external PCI buses that use the PCIe interface.

The i7-5820k is a strange case because it enables only 28 lanes. Intel's documentation does not explain how these lanes are organized or how the limit is enforced. Is the 8 lane port disabled completely along with a quarter one one of the 16 lane ports? Is the limit simply enforced at the link layer? I have no idea.
 
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