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AMD Radeon HD 5870 PCI-Express Scaling

Discussion in 'Reviews' started by W1zzard, Sep 16, 2009.

  1. Mussels

    Mussels Moderprator Staff Member

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    i tried telling people i only took a 10% performance hit on a 4x slot when i ran a 16x/4x crossfire setup, and no one beleived me.

    that was with 4870s on a 1.1 motherboard, at least i finally have someone else with similar findings now.
     
    SUPERREDDEVIL says thanks.
  2. W1zzard

    W1zzard Administrator Staff Member

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    i'll have the cf x8 and x4 numbers today as well
     
  3. tzitzibp

    tzitzibp New Member

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    *anxiously waiting* :twitch:
     
  4. qubit

    qubit Overclocked quantum bit

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    Really useful review, thanks. :toast:

    If the difference between 8x & 16x is so small on this new beast of a card, I'm sure that it practically disappears on older, slower cards (eg 8800 GTX, HD4850 etc) which most people will currently have. Therefore, we don't have to worry about losing performance in 8x mode. :)
     
    Last edited: Sep 24, 2009
  5. W1zzard

    W1zzard Administrator Staff Member

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    in x8 2.0 .. x8 1.1 is equivalent to x4 2.0
     
  6. T3kl0rd

    T3kl0rd

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    Great article. Can't wait for the CF results. Seeing as how I am choosing a X58 mobo over P55, it will be interesting to see the percentage decrease, to say the least. 10% or so is reason enough for me to go X58.
     
  7. yogurt_21

    yogurt_21

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    very interesting. I find it comforting that my 16x 1.1 bus will not penalize me nearly at all should I end up getting one of these cards. based on current budgeting, it seems to be ahard push to get anew gpou and upgrade cpu/mobo/memeory.

    thanks!
     
  8. sethk New Member

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    This is interesting because it gives you a preview of how well it could work in a ExpressCard docking station solution for a laptop, where you could conceivable game with a 5850/5870 connected to your latop through ExpressCard (essentially PCIe 1x), with better framerates than almost anything available for most laptops.
     
  9. the_pharaoh New Member

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    "Buy one of these accelerators now, and give them a neighborhood when they become more affordable, and you will have secured yourself future-proofing for quite long."

    Wow, what on earth does that even mean? Proof-reading please.
     
  10. Dan848

    Dan848

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    I have a version 1.0 Gigabyte P35-DS3R that uses PCIe x16, so, that would be the same as x8 in version 2.0 PCIe?

    Thank you,

    Dan
     
  11. jmcslob

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    Yes
     
  12. [I.R.A]_FBi

    [I.R.A]_FBi New Member

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    My P45 has three .. no more worries ..:)
     
  13. Bo_Fox

    Bo_Fox New Member

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    Awesome article.. havent seen an article like that in years! Kudos, W1z and btarunr!
     
  14. stupido

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    well, if possible, I would like to see the impact of chipset too... I mean compared P45, P55 and X58?
    this review was done on i7 machine, but what on i5 machine or Core2Quad?
     
  15. Mussels

    Mussels Moderprator Staff Member

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    it would be irrelevant. CPU bottlenecks would be the only thing that changed the results.

    Obviously, on a weaker system the maximum FPS would be lower, therefore the performance differential would decrease across the tests.
     
  16. matrices New Member

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    I'm a little confused by the analysis. Does your x4 simulation accurately emulate the actual x4 on the P55 PCH? In a review of x16/x4 P55 boards (Asus and Gigabyte), you wrote:

    "The top slot gets a full 16 lanes of PCIe 2.0 from the CPU, while the second slot harnesses four of the not-quite-second-gen PCI Express lanes built into the PCH. Intel labels the P55's eight PCI Express lanes as 2.0, but they only signal at 2.5GT/s—gen-one speed. That's still plenty of bandwidth for Gigabit Ethernet and most reasonable auxiliary storage configurations. However, it might be a hindrance to CrossFire configurations."

    I can't decipher that. Four "not-quite-second-gen" PCI-E lanes? So these are x4 PCI-E 1.0 lanes, not x4 PCI-E 2.0 lanes? Are they the same type that you measured in this simulation? And since some P55 boards have 8/8/4, is the "4" from there the same speed as the "4" in the board you reviewed above?

    Anandtech has already done the CF test with ATI 5870 in 16/16 versus 8/8, and we already know the difference is negligible there. What would be truly interesting is to test Tri-Fire and CF with Physx (with the hack) in 16/16/16 versus 8/8/4 (whatever "4" that may be).

    Also, while the continuing usefulness of the x8 slot means that older 750i/680i SLI boards and Intel P35 boards will not be bottlenecked by PCI-E bandwidth, the C2D and C2Q are definitely bottlenecked to some degree by SLI and CF, period. Very few people have done the analysis but there's an article at Guru3D conclusively demonstrating that in some games, dual-card CF/SLI is 50% more effective on the i7 than the C2D/Q. And Tri-SLI (and therefore presumably Tri-CF) is almost completely wasted on non i7/i5 chipsets, according to the numbers.
     
    T3kl0rd says thanks.
  17. sideeffect New Member

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    Nice article, it was very informative.

    Out of interest if you run PCI-E 2.0 8x at 125MHz Bus speed does that increase the bandwidth to 5 GB/s?
     
  18. Bo_Fox

    Bo_Fox New Member

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    Once again, an awesome article!
     
  19. Calle2003 New Member

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    What's up with Dawn of War 2 1280x1024 2xAA 8xAF?
    x4 and x8 fares better than x16! :eek:
     
  20. Bo_Fox

    Bo_Fox New Member

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    ^^ Hmm, what do you mean?
     
  21. Calle2003 New Member

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  22. Geofrancis

    Geofrancis

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    i am glad somone did an article like this it proves that my hd 4850 runs fine in my J&W MITX 780G board that only has 4x pci-e 2.0 slot along with all the next generation graphics cards.

    on another note why are none of the new ati graphics cards single slot? that was one of the great features of the card.
     
    Last edited: Nov 25, 2009
  23. zed011 New Member

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    Nowhere to be found?:wtf:
     
  24. Bo_Fox

    Bo_Fox New Member

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  25. TAViX Guest

    Guys, one question.

    I have an Asus P5Q Deluxe mobo with 1 PCI-E x16 and 2 PCI-E x8. I'm running now an 5770 on the main slot, but I'm thinking to buy another card and Crossfire-it. The question is, are those 2 cards going to run on x8 or only one of them? I'm also curious what's the performance drop between x16/x16, x16/x8 and x8/x8

    thanks.
     

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