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Dual GPU on a single PCB vs true CrossfireX or SLI

Discussion in 'Graphics Cards' started by Monkey_Business, Mar 5, 2010.

  1. Is there any difference performance-wise of having say Two Radeon HD 5870's in CrossFireX as opposed to having a single Radeon HD 5970? (Two HD 5870 cores on a single PCB)

    The Dual GPU card probably consumes much less energy than Two seperate graphics cards in a CFX setup of the exact same GPU type. The Radeon HD 5970's throughput is so massive, that even the PCIe 2.0 x16 bottlenecks it. A single slot, anyway.

    It isn't a major bottleneck, at least not until the next generation of graphics cards are released, with PCIe 3.0 x32 to go with it.

    It also costs less to buy the dual GPU card than to buy Two of the same GPU type. Two HD 5870's is $800 while an HD 5970 = $700.
     
  2. overclocking101

    overclocking101

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    the performance is better with 2 single cards, but not by much this was proven back in the 3870X2 days and holds true to date. but like you said power wise the dualie is better. current gen cards are said to not work with pci-e 3.0 kind of like agp to pci-e you know what im sayin? different slot. my opinion, get the 5970 but if you ae looking for that extra 200 points in 3dmark vantage then get dual 5870's, also the 5970 performs a bit lower on top of the normal performance drop due to the lower clocks/voltage.
     
  3. Flyordie

    Flyordie New Member

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    PCIe 3.0 isn't even finalized yet.. won't be so till 2H 2010.

    As for which is better-
    Depends, if you use a single card like the HD5870 vs HD5970 @ = clocks then in most cases the HD5970 would loose due to PCIe bandwidth issues.

    I think it only has what.. 8x PCIe lanes on the card?
     
  4. beyond_amusia

    beyond_amusia New Member

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    If the mobo can run 2 cards at x16 each, and not x16/18 or x8/x8, I'd say 2 cards are better.

    If it's x8/x8 on 2 cards, it's be roughly the same as 2 GPUs on one card since they'd be sharing the same x16 link - so I theorize at least.
     
  5. Super XP

    Super XP

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    Yesterday the HD 3870x2 slightly fell behind 2 x HD 3870's in Crossfire due to the fact the chip that communicated between both GPU’s bottlenecked the crap out of the card. ATI quickly learned and fixed the problem sort of by increasing the bandwidth speed between the two with the HD 4870 x2 which did take back the performance crown over 2 x 4870's in Crossfire, but not by much.
    Today the HD 5970 is indeed much better designed and is shown to be somewhat faster in most cases than 2 x HD 5870's in Crossfire depending on which game you run. But we are not talking about slaughterous performance increases, but minimal at the most.
    Personally I would go for a single HD 5970 because it costs cheaper than buying 2 HD 5870's, and later on you can always add a 2nd card when prices come way down IMO.
     
    nt300 says thanks.
  6. Super XP

    Super XP

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    If my memory serves me well, there is no bandwidth issue, it was proven over and over again these graphics cards don't even come close to using up that bandwidth. But obviously IMO you would expect slight performance improvements with x16 over anything less.

    This review is approx: 2 years old but from a reliable source IMO. They also benched the HD 3870x2 which is already a bottleneck within itself along with the HD 2900 series.
    Crossfire X8 + X8 Versus X16 + X16
    http://www.tomshardware.com/reviews/crossfire-meets-pci-express,1761-4.html
     
    Last edited: Mar 6, 2010
    nt300 says thanks.
  7. Indra EMC

    Indra EMC

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    couple of HD 5870's are faster than single HD 5970 even it's using dual GPU.

    that's because HD 5870 using 850Mhz Clock and 4.8 Ghz Memory Clock.

    HD 5970 only 725 Mhz core clock (similar with 5850) and only use 4.4 Ghz memory clock.

    couple of 5870 draw more power on your PSU than single 5970, also need four 6-pin PCIE connector (Both of 5870 are using two 6 pin PICE)
     
  8. Mussels

    Mussels Moderprator Staff Member

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    1. no. the only difference is that dual GPU cards tend to have lower clocks.

    2. They consume the same amount as two cards in many cases. its the same amount of GPU's and the same amount (and type) of ram, why would it be different?

    3. even PCI-E 2.0 8x doesnt bandwidth limit high end dual GPU Cards much. w1zzard tested that.

    4. that is true, sometimes the dual GPU cards are cheaper. but in the end, its still crossfire (or SLI)
     
  9. sttubs

    sttubs

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    Don't forget the 5970 can be easily overclocked, but so can the 5870's.
     
  10. nt300

    nt300

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    The benefit of dual GPU is both of these GPU's communicate with each other much more efficiently than 2 seperate GPU's in crossfire. The dual-GPU HD 5970 is the better value if u plan on buying 2 HD 5870's. Crossfire doesn't always scale all that good sometime.
     
  11. erocker

    erocker Super Moderator Staff Member

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    If a game doesn't scale well with CrossFire, it won't scale well with a dual ATi GPU either.
     
  12. If you're getting poor performance, or noticing extremely little performance boost with more than a single GPU. Such as having an HD 4870 and then buying another HD 4870 and xfiring it, it's probably a GPU/CPU bottleneck.

    The only processor to not have any bottleneck with any GPU setup is a Core i7 @ 4.5 GHz. A CPU at that speed demands expensive water cooling.
     
  13. nt300

    nt300

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    Since when? Today CPUs don't bottleneck graphics anymore, maybe in the past but not anymore. Check out real world gaming benchmarks and you will see for yourself Phenom II's keep up with i7's no problem. I can see problems with Pentium 4's and Athlon 64's back in the day but not anymore.

    I think harddrives do a better job bottlenecking your system.
     
  14. Mussels

    Mussels Moderprator Staff Member

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    no they dont. they communicate via PCI-E lanes and crossfire/SLI bridges like the other cards. there is NO advantage there.
     
  15. The hard drive is naturally the slowest part of any computer. But SSD's have relieved that problem somewhat. While sacrificing storage space for speed, and also being on the expensive side.
     
  16. Lionheart

    Lionheart

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    Consider the supa dupa expensive overpowered soon to be launched HD5970 4gb cards:D
     
  17. GTA IV uses almost 4GB of texture memory on it's maximum resolution.
     
  18. Mussels

    Mussels Moderprator Staff Member

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    these 4GB cards are 2x2GB, only 2GB is usable.

    i doubt GTA IV can use that much texture ram, or it wouldnt be playable on any 32 bit systems - and would run even worse than it does on 64 bit sytems.
     
  19. Lionheart

    Lionheart

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    Is it because the depth of field takes up so much memory in that game!
     
  20. Mussels

    Mussels Moderprator Staff Member

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    DOF is a post process effect, has nothing to do with texture size or ram usage
     
  21. Lionheart

    Lionheart

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    Well cheers for clearing that up for me:cool:
     
  22. erocker

    erocker Super Moderator Staff Member

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    I can believe GTA IV to use close to 4gb of memory. It's an incredibly horribly coded game. Texture optimization is zero. Still it's a damn fun game, I guess I need an actual 2gb card to try it out on first. I would love a 2gb "5890" type card right now. I could then have some slots back.
     
  23. nt300

    nt300

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    Didn't you hear only 1GB would be used out of the 2GB your card has.
     
  24. erocker

    erocker Super Moderator Staff Member

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    I have two 5850's that use 1gb. A 5970 is able to use 1gb. I said I would like to have a 5890 single GPU "type" card with 2gb total RAM.

    From a previous thread:

    It counts two single units with 1gb of ram allocated to each individually. :toast:
     
  25. Super XP

    Super XP

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    I'm saving up my pennies for a nice HD 5970:D which means I am going to probably sell my 2 x HD 4870's along with a few other stuff including my StealSeries 3H USB 8ch headphones. But this all depends on how well NVIDIA does and how much ATI is willing to drop the price.
     

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