Will my PC be ready for a 2 R9 290X's?

Discussion in 'Videocards - AMD Radeon' started by Vinnie, Sep 30, 2013.

  1. yasamoka

    yasamoka Ancient Guru

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    Interesting question. Got one idea to throw here. This is my own conclusion based on data available.

    Know why PCI-E version and # of lanes affects configurations with multiple (Nvidia) graphics cards on multiple high resolution monitors? It's because Nvidia is already using PCI-Express to transmit data (frames and split frames) between cards.

    The question is this: why would we need higher bandwidth than one or two cards would need if we're simply using more cards? Isn't data equally transmitted and VRAM mirrored across all cards? Isn't it the only obvious difference that the CPU is simply pushing more FPS now?

    From that data we can extrapolate PCI-E bandwidth requirements for bridgeless CrossFire at the extreme end of the scale. On a single monitor AND / OR one or two cards, the bandwidth requirements would likely be a bit higher than bridged CF. All in all, with increasing resolutions, refresh rates, and number of monitors, passing data over the bus that is not very populated anyways (PCI-E) is the smartest decision, and I bet that Nvidia will be into bridgeless SLi soon as well. Let's face it, that bridge is useless if you're using it for single monitors (or low requirements in general) since that has a minimal bandwidth requirement relative to what PCI-Express offers.
     
    Last edited: Oct 2, 2013
  2. sykozis

    sykozis Ancient Guru

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    Why wouldn't they? They have to fully support PCIe 2.0, by specification. The rest is purely software. If crossfire doesn't work, it's due strictly to a software limitation, not hardware. NVidia made SLI work without the SLI bridge being connected, though it was only supported on certain cards.....

    NVidia used to support bridgeless SLI on mid-range cards.
     
    Last edited: Oct 2, 2013
  3. k3vst3r

    k3vst3r Ancient Guru

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  4. yasamoka

    yasamoka Ancient Guru

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    True. So was CrossFire bridgeless at some point, I think. PCI-Express 1.0 didn't have enough for bridgeless back then, it seems.
     

  5. warlord

    warlord Ancient Guru

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    why should they care? all their new mobos and next chipset/cpu will support pciex 3.0 and if you have the money to buy 2 or more 290s then it's sure for them that you can upgrade your whole system.
     
  6. Vinnie

    Vinnie Ancient Guru

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    So guys, they have been released now. Will my PC still be ready to Crossfire two of these babies? Will PCI-E 2.0 handle it?
     
  7. eclap

    eclap Banned

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  8. Vinnie

    Vinnie Ancient Guru

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    Alright, I will order two then. Thx! :)
     
  9. Vinnie

    Vinnie Ancient Guru

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    They will be here in 2/4 days. :)
     
  10. kazama

    kazama Master Guru

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    How are running the cfx with pci 2.0 vinnie? compared it to the bench with 3.0?
     

  11. Vinnie

    Vinnie Ancient Guru

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    I will test it out in a few days. They haven't arrived yet.
     
  12. Ecurb

    Ecurb Member

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    Hi guys,

    I picked up 2 x 290x's today that will be putting in Crossfire on the weekend (to replace my 4 x GTX 680s) My MB (asus maximus vi extreme) has the option to set PCI lane speeds manually so i can try PCI-E 3.0 x8 versus PCI-E 2.0 x16, x8 et al and report and differences. What do you think is a good benchmark to run for this and ill post up in the coming days.

    Ecurb
     
  13. Vinnie

    Vinnie Ancient Guru

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    3DMark 2013 of course. :)
     
  14. Vinnie

    Vinnie Ancient Guru

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    Guys, will my motherboard be a bottleneck? I just found out the when I have two cards installed, the PCI-E 2.0 speed falls back on 8x for both slots.
     
  15. Vinnie

    Vinnie Ancient Guru

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  16. eclap

    eclap Banned

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    I can only see pci-e 2.0 in the spec.

    Pci-e 2.0 at 8x8 will be fine
     
  17. Vinnie

    Vinnie Ancient Guru

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    Even if CrossfireX runs over PCI-E (without a bridge)?
     
  18. Hilbert Hagedoorn

    Hilbert Hagedoorn Don Vito Corleone Staff Member

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    8x gen 2.0 is a ****load of bandwidth. Realistically you might see a few % difference over x16 or x8 Gen 3.0 tops. Do not worry about this at all.

    And as to the other question the mobo being Gen 3.0 compatible, no you need a Gen 3.0 compatible CPU to make use of Gen 3.0 ports.

    You main worry will need to be whether or not to invest in an airco in your room, two of these puppies will exhaust a lot of heat my friend :nerd:
     
  19. Vinnie

    Vinnie Ancient Guru

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    Thanks Hilbert! Have you tested, by coincidence, tested two R9 R290X's with PCI-E 2.0 x8?
     
  20. eclap

    eclap Banned

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    yes, it's been confirmed by AMD that pci-e 2.0 is perfectly fine for bridgeless crossfire. you have nothing to worry about.
     

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