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ROG Rampage VI Extreme PCIe lanes configuration and distribution: new build advice

Discussion in 'General Hardware' started by Dmitry, May 16, 2018.

  1. Dmitry

    Dmitry New Member

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    Hi!

    Can you please help me to understand how PCIe lanes and slots are operating and distributed for ROG RAMPAGE VI EXTREME on Core i9-7900X (44 PCIe lanes) in order to make my build and configuration possibe.

    My ultimate goal is to have 2 graphics cards in SLI mode together with storage subsystem made up from Intel Optane 905p PCIe x4 add-in card (available also in U.2 variant) for OS drive and either one or two Asus Hyper M.2 X16 card with total number of four M.2 PCIe x4 drives (e.g. Samsung 960 PRO 2TB) in VROC non-bootable RAID0 for data storage. No any other additional drives are going to be used (neither M.2_1 nor M.2_2).

    Is generally such confiuration possible and which slots should I use for the components to work properly?

    For instance, according to the manual x16/x8/x8/x8 PCIe configuration is supported, though as far I undestand only slots PCIex16_1 and PCIex16_3 could be used for graphics card and only 4 lanes are left available for PCIx8_4 slot while PCIex8_2 is disabled. How many lanes are left for other slots in reality? Will the rest of PCIx8_2 and PCIex8_4 slots be able to accomodate two Hyper M.2 X16 cards to operate in x8 mode each with two M.2 x4 drives in each of them and be able to create non-bootable VROC RAID0, and still use PCIex4_1 for Intel Optane 905p PICe x4 add-in card, or U.2 variant? Should I better use Intel M.2 drives (e.g. Intel 760p series) for VROC to work properly?

    Which PCIe slots are supporting PCIe bifurcation? Is it possible to accomodate 2 graphics card working in x8 mode via PCIe riser in PCIex16_1 slot and use PCIex16_3 slot for Asus Hyper M.2 X16 card in x16 mode, and PCIex8_4 slot for Intel Optane 905p x4 PCIe drive card?

    What happens if I insert graphics cards to slots PCIex8_2 and PCIe16_3, will the system operate and how many lanes are left for other slots?

    This subject is bit confusing and not self-explanatory from the manual, unfortunately. But the cost of equipment makes me stay 100% sure beforehand that it will work properly as it should.

    Thank you in advance for help and understanding!!
     
  2. Agent-A01

    Agent-A01 Ancient Guru

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    You can use PCIex16_1 and 2 for SLI.

    PCiex16_3 is a 16 lane, while PCie 2 is only 8x lane, hence the recommendation to use the 3rd slot for SLI to get best performance.

    As for having 2 x16 hyper(what's the point if it will support 4 M.2 cards?), they'll both run at 8x speeds.

    So total lanes will be 16x + 8 + 8 + 8, which leaves 4 remaining lanes.
    You would need to use M.2 #1 slot or U.2(u.2 shares with M.2#1 slot) to be on the safe side.

    I see that using M.2 #2 will force PCIe #3 to 4x lanes.

    Also, thunderbolt device will take 4x lanes(user configurable on which slot it uses).

    But I'd say that setup will safely work, there's enough configurable options.
     
  3. Dmitry

    Dmitry New Member

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    Hi! Thank you. I am totally fine with x8 mode for graphics cards each, the bandwith is totally enough.

    What I was not sure, what happens if VGA cards are in slots 2 and 3. The system might check for the presence of video card in slot 1 and does not proceed further if not found.

    In case it is possible, then x16 slot 1 could go for a Hyper M.2 X16 card with 4 M.2 drives and still slot 4 left for PCIe x4 card Intel Optane 905p drive.

    I have also spotted X299 ITX board with single x16 slot to be splitted with PCIe riser/splittet into two x8 slots with working SLI setup due to PCIe bifurcation support of X299.
     
  4. Agent-A01

    Agent-A01 Ancient Guru

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    Should still work in slot 2 and 3.

    Single card works in slot 2 and 3 so SLI should have no issues.
     

  5. Dmitry

    Dmitry New Member

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    Great then. Thank you!
     

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