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PCIe lanes: CPU vs motherboard for X99

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1 hour ago, goof doofus said:

Then I think things are becoming a bit clearer. In the PCIe lane diagram, it seems like all the x16 slots go to CPU lanes and all the rest take up the additional 8-ish motherboard non-CPU lanes. Is that right? 

 You hit the nail on the head!

 

1 hour ago, goof doofus said:

Can non-GPU PCIe peripherals go in either? Could I put PCIe ssd's and wireless adapters in both x16 and x1 slots, depending on what's available after the GPUs?

Absolutely!  A great example of this is if you wanted to run a RAID 0 with two PCIe M.2 drives like a 950 Pro.  One M.2 would run off of the chipset PCIe lanes while the other would run through the CPU PCIe lanes.  Of course x99 does not support M.2 hardware RAID, but doing it through Windows works fantastic and is just as fast if not faster contrary to popular belief.  This solution has netted me 5 GB/s reads and 3 GB/s writes.  This has a big advantage over something like running two or three M.2 drives via the DMI 3.0 of a Z170 board as it would be limited to roughly 3 GB/s in both directions and two let alone three fast M.2s would saturate the platform. 

 

Hope that helped.

I'm trying to find out more about PCIe lanes for the Intel i7 5930k / ASUS X99 A II build I'm planning, and I'm having trouble gathering information. The CPU has 40 PCIe lanes, the motherboard has its own set of 40 PCIe lanes, and there is not always a one-to-one correspondence between sets. Apparently, some motherboard PCIe lanes don't go to the CPU. Also, I'm having trouble finding out if slots like M.2 and SATAe use up some of the 40 formal CPU PCIe lanes without using any motherboard PCIe lanes. I haven't been able to find the diagrams I'm looking for in the manual or online. I want to be able to look at any slot in the motherboard layout schematic and know how many of the formal 40 motherboard PCIe lanes it uses, how many of the formal 40 CPU PCIe lanes it uses, how many CPU PCIe lanes connect to motherboard PCIe lanes, and where all the lanes are routed in general.

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2 minutes ago, goof doofus said:

I'm trying to find out more about PCIe lanes for the Intel i7 5930k / ASUS X99 A II build I'm planning, and I'm having trouble gathering information. The CPU has 40 PCIe lanes, the motherboard has its own set of 40 PCIe lanes, and there is not always a one-to-one correspondence between sets. Apparently, some motherboard PCIe lanes don't go to the CPU. Also, I'm having trouble finding out if slots like M.2 and SATAe use up some of the 40 formal CPU PCIe lanes without using any motherboard PCIe lanes. I haven't been able to find the diagrams I'm looking for in the manual or online. I want to be able to look at any slot in the motherboard layout schematic and know how many of the formal 40 motherboard PCIe lanes it uses, how many of the formal 40 CPU PCIe lanes it uses, how many CPU PCIe lanes connect to motherboard PCIe lanes, and where all the lanes are routed in general.

tell me all of what you're using. most of them go to the expansion slots and m.2 slots, among a few other things

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1 minute ago, RGProductions said:

tell me all of what you're using. most of them go to the expansion slots and m.2 slots, among a few other things

I'm really just beginning to plan my build, so I don't have many specifics. I plan to use one GPU for graphics and another for programming in CUDA. I want to use the rest of the PCIe lanes for ssd's if I can. All the while, I'm thinking about whether I can give up 12 CPU PCIe lanes to downgrade to the 5820k and save $200. To plan all this, I feel like I need more detailed schematics about PCIe that directly relate to the motherboard layout diagram.

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2 minutes ago, goof doofus said:

I'm really just beginning to plan my build, so I don't have many specifics. I plan to use one GPU for graphics and another for programming in CUDA. I want to use the rest of the PCIe lanes for ssd's if I can. All the while, I'm thinking about whether I can give up 12 CPU PCIe lanes to downgrade to the 5820k and save $200. To plan all this, I feel like I need more detailed schematics about PCIe that directly relate to the motherboard layout diagram.

either will work :) don't stress it

M1 MacBook Air 256/8 | iPhone 13 pro

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Just now, RGProductions said:

either will work :) don't stress it

That's good to hear. It's also really cool to see how everything connects to everything else, so I'm still holding out for more granular detail for curiosity's sake.

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Just now, goof doofus said:

That's good to hear. It's also really cool to see how everything connects to everything else, so I'm still holding out for more granular detail for curiosity's sake.

the 2 cards use up to 16 each, but work fine at 8, and sata ssds don't use pci lanes

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1 minute ago, RGProductions said:

the 2 cards use up to 16 each, but work fine at 8, and sata ssds don't use pci lanes

 

Actually, SATA SSDs do use PCIe lanes via the x99 chipset. 

 

 

19 minutes ago, goof doofus said:

I'm trying to find out more about PCIe lanes for the Intel i7 5930k / ASUS X99 A II build I'm planning, and I'm having trouble gathering information. The CPU has 40 PCIe lanes, the motherboard has its own set of 40 PCIe lanes, and there is not always a one-to-one correspondence between sets. 

 

The x99 chipset supplies 8 PCIe lanes on it's own.  The 5830k would supply 40 PCIe lanes.

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You could always get a X99E-WS. It has a PLX chip on board so you get extra PCIE lanes.

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20 minutes ago, done12many2 said:

The x99 chipset supplies 8 PCIe lanes on it's own.  The 5830k would supply 40 PCIe lanes.

How did you find that out? The diagram below only shows 7 extra mb lanes. I'm also confused about the second x1 slot from the left since it doesn't appear on the X99 A II.

 

05-diagram_pcie_routing_40lane.gif

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4 minutes ago, goof doofus said:

How did you find that out? The diagram below only shows 7 extra mb lanes. I'm also confused about the second x1 slot from the left since it doesn't appear on the X99 A II.

 

05-diagram_pcie_routing_40lane.gif

 

I try to go straight to the horse.  :D

 

The difference between 7 and 8 is kinda small, but I was initially addressing the fact that you said that the motherboard had 40 PCIe lanes of it's own, which is not possible.

 

http://www.intel.com/content/www/us/en/chipsets/performance-chipsets/x99-chipset.html

 

 

Capture.JPG

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4 minutes ago, done12many2 said:

you said that the motherboard had 40 PCIe lanes of it's own, which is not possible.

Then I think things are becoming a bit clearer. In the PCIe lane diagram, it seems like all the x16 slots go to CPU lanes and all the rest take up the additional 8-ish motherboard non-CPU lanes. Is that right? Can non-GPU PCIe peripherals go in either? Could I put PCIe ssd's and wireless adapters in both x16 and x1 slots, depending on what's available after the GPUs?

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1 hour ago, goof doofus said:

Then I think things are becoming a bit clearer. In the PCIe lane diagram, it seems like all the x16 slots go to CPU lanes and all the rest take up the additional 8-ish motherboard non-CPU lanes. Is that right? 

 You hit the nail on the head!

 

1 hour ago, goof doofus said:

Can non-GPU PCIe peripherals go in either? Could I put PCIe ssd's and wireless adapters in both x16 and x1 slots, depending on what's available after the GPUs?

Absolutely!  A great example of this is if you wanted to run a RAID 0 with two PCIe M.2 drives like a 950 Pro.  One M.2 would run off of the chipset PCIe lanes while the other would run through the CPU PCIe lanes.  Of course x99 does not support M.2 hardware RAID, but doing it through Windows works fantastic and is just as fast if not faster contrary to popular belief.  This solution has netted me 5 GB/s reads and 3 GB/s writes.  This has a big advantage over something like running two or three M.2 drives via the DMI 3.0 of a Z170 board as it would be limited to roughly 3 GB/s in both directions and two let alone three fast M.2s would saturate the platform. 

 

Hope that helped.

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  • 1 year later...

Hi,

 

I know this thread is old-ish now but relevant to this.  I was stressing about the chipsets on various platforms such as Z97, X99, Z170, Z270 etc......

 

I became aware of the Intel Flexi I/O system with the PCH that connects the chipset to the CPU.  I uploaded Intel I/O assignments for X99 chipset.

 

I've got one for Z270 which is the same as for X299 apparently.

 

Please bear in mind that the CPU can have 28 or 40 PCI-e lanes for the CPU + 8 PCI-e lanes for the chipset - I'll post more later, thanks

Paint Edit X99 jpeg.jpg

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