PCIE Bifurcation

Discussion in 'Small Form Factor Systems' started by jb1, Jul 28, 2015.

  1. C_Payne

    C_Payne [H]Lite

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    I have also in the past weeks developed some new Risers.

    I can provide any combination of x8, x4 and M.2, custom dimensions and mounting holes etc.

    This for example is meant to extend a mini ITX Board to fit into an mATX case with one x8 GPU and two additional x4 slots.


    ITX.jpg

    IMAG1846.jpg


    This is all the PCBs I have around:

    IMAG1935.jpg

    I am working on a small webshop to sell them in the future.

    Also Asrock has been nice enough to enable x4x4x4x4 on their x99e itx/ac if anyone needs that bios please let me know.
     
  2. Neapolitan6th

    Neapolitan6th Gawd

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    That's awesome. I enjoyed watching everyone in the comments on that one freak out because they'd never heard of PCIE bifurcation before.

    I'm curious, with PCIE 4.0 on the somewhat near horizon, do you think your crop of bifurcated risers will be forward compatible with the new standard?

    2 x8 4.0 lanes is quite a lot of bandwidth to play with.
     
  3. C_Payne

    C_Payne [H]Lite

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    Well I cant be sure, but I do think so.
    The Clock-Buffer I choose is gen 4 compliant already.

    However:
    PCIe gen4 connectors are improved versions and only SMT.
    However:
    I have followed good practice with my Design. I read this paper, and seem to comply to most of these standards already. http://www.oldfriend.url.tw/article/IEEE_paper/SI/Intel_PCIe connector 16G_DesignCon2016_p89~.pdf
    However:
    I routed for an impedance Target of 100Ohms, it should be 85 now.
    However:
    In typical ITX build trace length is short.
    However:
    PCIe gen4 per spec only allows one connector between endpoints.
    However:
    PCIe gen3 allows for two connectors between endpoints yet this works without impact on bandwidth (I have tested bandwidth with an nice Nvidia Cuda Porgram)
    These are 7 Connectors between endpoints. A lot of users have actually been stacking more then one riser without issues.
    IMAG2062.jpg

    I will find out and certainly make a redesign should they not work.
    I dont think one would really need to use retimers as it would make them more expensive by an order of magnitude.

    But I do think that the common setup with flexible risers may not work anymore.
     
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  4. chemist_slime

    chemist_slime [H]ard|Gawd

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    Would love to get the x4x4x4x4 bios for the asrock x99e-itx/ac. Also, do you have an x4x4x4x4 riser? Thanks.
     
  5. C_Payne

    C_Payne [H]Lite

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    I currently have no x4x4x4x4 PCBs on hand, but I could make one to your spec. Just drop an email risers@peine-braun.net, I will send you that bios.
     
  6. TristanDuboisOLG

    TristanDuboisOLG n00b

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    I was wondering, I found this bifurcation chat some time ago while researching. I'm having some trouble getting my bifurcated setup working, normally I know how to troubleshoot stuff, but this is getting into the realm of "never even heard of that" for most people.

    My setup so far:
    Asrock x99e-ITX a/c (With modded bios from Asrock Eng dept)
    Asus Hyper M.2 x16
    1x Samsung 960 Pro NVME (Boot)
    4x Intel 660p 512GB

    I've got windows server loaded onto the boot drive, gone through the nightmare that is LAN drivers for this board on Windows Server (not provided and cannot install), even managed to get the wireless card working. Now I'm having issues with getting my Hyper M.2 working. Sometimes it boots and recognizes it, other times it doesn't. I've heard other people mention that when they have issues with their Hyper m.2 cards and they don't recognize drives the LED lights on the side will turn off. So if you have 1 m.2 connected, one light will be on, 2 is two lights and so on and so forth. My device (when it powers up) has all 4 lights on but only shows one 512gb drive in disk management. Is there any way to troubleshoot this?

    I have emails from ASUS where they explain to me that I was correct in some earlier inquiries and that the Hyper M.2 will work with any motherboard that has x4x4x4x4 bifurcation enabled AND I have the modded Bios from Asrock that enables x4x4x4x4 bifurcation. They mention that x8x8 works correctly, I'm going to try to change over the bios to x8x8 tonight in order to see if that enables a second drive. I'd love any other suggestions that anyone might have.


    . Asrock Support.JPG Asus Support.JPG
     
  7. C_Payne

    C_Payne [H]Lite

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    Asrock x99e Bifurcation BIOS including x4x4x4x4:
    https://peine-braun.net/public_files/Bifurcation_BIOS/X99EITX3.81A
    I hope asrock won't mind me sharing this with you publicly.

    Also I am currently writing a summary on PCIe Bifurcation, so if you have a working Bifurcation Setup please drop an eMail to risers@peine-braun.net or PM with your mainboard, bios revision or mod-bios and tested modes (e.g x8x8, x8x4x4).
    That would be great.
     
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  8. Smitty2k1

    Smitty2k1 Gawd

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    This is all seriously [H] level stuff. Good job y'all.
     
  9. rekrek

    rekrek n00b

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    Hi C_Payne, I am really interested in the card that "extend a mini ITX Board to fit into an mATX case".
    I hope you will be able to put some up for sale. I would recommend selling on ebay as it will do all international shipments.
    What price can you expect to sell them ?

    Would use it in a NAS to add additional ports (ethernet and 10gbe) to use as a cheap and energy efficient router with integrated switch (with 10gbe !). Thanks
     
  10. C_Payne

    C_Payne [H]Lite

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    I have been working on my Online shop and the PCIe bifurcation summary I have been talking about:
    It supports Paypal Express Checkout.

    https://peine-braun.net/shop/

    There is also some information I have collected concering bifurcation there, this is however work in progress. Any additions would be greatly appreciated, please drop a pm or eMail.

    https://peine-braun.net/shop/index.php?route=information/information&information_id=7

    You can still always drop me an eMail
    risers@peine-braun.net
     
  11. Prodeous

    Prodeous n00b

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    I have a general question on the Bifurcation. If you split a slot to 4x4x4x4, and plug in a 8x pcie device. Would the device use a single 4x slice, or would it recombine the two 4x ?

    I have Gigabyte Designare x399 board, and all it can do is split slots to multiple of 4x in BIOS. And I would prefer 8x splits.
     
  12. C_Payne

    C_Payne [H]Lite

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    Unfortuantely that will not work, maybe it wont even POST.

    However it will probably be easy to mod that BIOS to support x8x8 as well...

    EDIT: ohh its x399... not sure about AMD BIOS modding

    EDIT2: checked the bios briefly, dont think it can be done easily with modding tools
    However Gigabyte may add it, just write a support request to them. Shouldnt be to much work for them.
    Asrock has in the past replied positively to requests like this
     
    Last edited: Jan 28, 2019
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  13. superray

    superray n00b

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    Although I'm not interested SLI, it's useful to set up multiple pci-e ssds this way
     
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