SLI and Unreal 4 engine.

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by venturi, Dec 10, 2015.

  1. venturi

    venturi Master Guru

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    GPU:
    dual 3090 FE SLI
    I'm having a tough time actually getting any performance out of quad or dual SLI with titles with Unreal 4 engine,

    When building the profile in nvidia inspector, I'm able to get all 4 cards to work with the games, all 4 yards get warm, all 4 gpus seem to get bust, but the game has amazing stutter and lag. Using one card only seems to work better, but at 4096x2160 it is still not good enough,.

    So for unreal 4 games, how or what needs to be done:

    Compatibility bits? Dx1 compatibility bits>? Multichip? etc
    I've set the profiles to use 4gpu, AFR1 or AFR2 ---show a lot of stutter.

    I realize that the unreal 4 engine uses temporal AA, which I don't like so I have that disabled. Even with no antialiasing its full of stutter and lag.


    So I'm asking:
    What magical combo in invidia inspector do i use to get sli with the equivalent perf that is higher than using a single card?


    thank you
     
  2. BangTail

    BangTail Ancient Guru

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    There is no 'magical combo' the engine is known to be SLI/CF unfriendly.

     
  3. venturi

    venturi Master Guru

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    GPU:
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    I agree with you,
    but one card, can't do decent frame rate at 4096x2160 with most of the desirable eye candy.

    Seems a shame not to utilize the other 3 cards.

    Except for unreal 4, I've had a 100% success in quad SLI. However that success was paved with blood and bone and took a lot of effort).

    With unreal 4 engine I really don't have a way to get effective SLI.
    I got SLI working, but with little benefit other than using more electricity and converting it to heat.
     
  4. GuruKnight

    GuruKnight Master Guru

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    Be careful about generalizing regarding UE4 and SLI.
    True, that especially temporal AA tends to break SLI in some UE4 games.
    But this is mostly due to PCI-E bandwidth limitations.
    Perhaps the engine still needs more work to become fully AFR friendly.

    And some UE4 games scale nice with SLI, such as "The Vanishing of Ethan Carter Redux" and "Daylight".
    Unreal Tournament Pre-Alpha is in such an early state of development, that I wouldn't conclude anything yet honestly.

    I still would say, patience is the keyword here :)
     

  5. fantaskarsef

    fantaskarsef Ancient Guru

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    What scaling or problems did you see at 2way SLI with your TXs, if I may ask?
    And I wonder if this will mean improved or crippled performance under dx12 with SLI/CFX systems.
     
  6. GuruKnight

    GuruKnight Master Guru

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    Well, Unreal Tournament Pre-Alpha requires full 16x speed on both PCI-E 3.0 slots to scale decent with 2-way SLI (0x080000F5), and "The Vanishing of Ethan Carter Redux" needs 0x080600F5 for the best scaling.
    In both games temporal AA breaks scaling fully, unless you run at PCI-E 3.0 16x on both cards.

    And I can only imagine these PCI-E limitations become an even larger bottleneck with 3-way SLI.
    Here is a post I made about Ethan Carter Redux:
    http://www.forum-3dcenter.org/vbulletin/showpost.php?p=10793174&postcount=2048
     
    Last edited: Dec 10, 2015
  7. venturi

    venturi Master Guru

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    GPU:
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    Thank you, I will try some of your suggestions this evening and report back

    Coincidentally, I have the Vanishing of ethan Carter Redux as well so I will compare and see what i can do with 4GPU

    On temporal AA.
    My inmpression is that it makes many fine details blurry and dithery. Almost to the point that plain FXAA seems crisper with almost the same benefits - just my humble opinion
     
  8. venturi

    venturi Master Guru

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    Thank you, the profile and setting from the link worked well.

    THANK YOU!
     
  9. dreamss

    dreamss Banned

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    i assume fable legends is the same case
     
  10. ESlik

    ESlik Ancient Guru

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    Just curious venturi, what drivers are you running?
     

  11. dreamss

    dreamss Banned

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    no fable dint work with that flag sadly

    im getting 60-90 fps on UT4 with 0x080000F1 had to turn down the effects to med and im seeing 77% bus usage on x58 sli with dual 680s, gpu usage is 66-75%

    im using 361.42 drivers
     

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