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crossfire cards :do they need same bios ?

Discussion in 'AMD / ATI' started by abbutec, May 6, 2013.

  1. abbutec

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    Hallo , i have a amd7970 and a gigabyte7970 .For crossfire do they need the same bios and same clock frequencies? or doesn't it matter. it's a saber x79, i7-3930. Thanks for answers.
     
  2. de.das.dude

    de.das.dude Pro Indian Modder

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    no. but performance will be based on the slower card.
     
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  3. BarbaricSoul

    BarbaricSoul

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    Don't think that is right for crossfire, otherwise crossfiring a 7970 with a 7950 would be the same as having two 7950, which it is not.
     
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  4. puma99dk|

    puma99dk|

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    but won't the card running the highest clock speeds clock down to what the card running the slowest clock speeds run?

    ino it does that for Nvidia Sli, but not 110% sure with X-Fire/CrossFire since u can mix GPU's like HD7970 and HD7950 not something u can with Nvidia unless u use anatolymik's HyperSli patch that ino ^^;
     
  5. BarbaricSoul

    BarbaricSoul

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    IIRC, it didn't do that when I was running 5870 crossfire
     
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  6. [Ion]

    [Ion] WCG Team Assistant

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    The way it works is that both cards clock/cut themselves down to the lowest one. So if I crossfired my HD7950 and my Tahiti LE HD7870, they'd both cut down to 2GB vRAM, 1536 shaders, and the slowest clock speed.


    abbutec, you don't have to flash the BIOS, but it would be worth your effort to use software to set them to the same speed on the core/RAM

    EDIT: Apparently I'm wrong :eek:
     
    Last edited: May 7, 2013
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  7. Mussels

    Mussels Moderprator Staff Member

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    nope. i ran a 5850 and 5870 crossfire for about a year, and they do not need to match clocks.


    ram definitely cuts down, but the clocks dont need to - you can overclock them to different levels as well, its just not going to be the same gains from OC'ing a single GPU
     
    Last edited: May 7, 2013
  8. cadaveca

    cadaveca My name is Dave

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    +1. It's only memory size that is adjusted, everything else is independent to each GPU.
     
  9. puma99dk|

    puma99dk|

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    oh oki, then i learned something new here :D
     
  10. The Von Matrices

    The Von Matrices

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    This is new information to me. I have 3 cards, so would the best performance be to have them all their maximum individual clock speeds or would that be no different than having them all at the clock speed of the slowest card? Is there an advantage to having them all at the same clock speed?
     
  11. ste2425

    ste2425

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    Wouldn't the faster card be bottlenecked the slower one slightly? don't they have to work in time other wise you get video issues? So the faster card might perform its processing faster but will still have to wait on the slower to finish its work before the faster can continue on the next job? Otherwise what ever the faster card is processing will be finished and outputted before the slower card has outputted its work which could need to be outputted simultaneously? Same reason VRAM is duplicated? Ive only been using Xfire for a little while so all my basic ideas here could be WAY off.
     
  12. de.das.dude

    de.das.dude Pro Indian Modder

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    wow. so amd cfx is better than nvidia SLI!
     
  13. BarbaricSoul

    BarbaricSoul

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    Depends on how you look at it. Both have their pros and cons. Crossfire does give more option as to what cards can work together, but you also have to worry about having the proper crossfire profiles installed on your computer for crossfire to work. SLI is more restrictive as the what cards can work together, but if a game is coded to run SLI, you don't have to worry about installing any SLI profiles for it to work like you do with crossfire.

    SLI= easier to use
    crossfire= more options for cards to use
     
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  14. d1nky

    d1nky

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    that's what I thought and read before, Im planning on xfiring soon and thinking about adding a 7970. ive seen many times that the more powerful card decreases to match the weaker card for this exact reason.

    and the guys above saying otherwise has me all confused lol

    id still oc the 7950 to match or have a 1200/1600 oc on both.

    clarity please?
     
  15. cadaveca

    cadaveca My name is Dave

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    What I and several others posted is how it is.


    Nothing changes but memory size. As to whether it's optimal to have equal cards or not is not something I care to delve into. :p

    I prefer matched cards, but used both 7950 and 7970 together, with 7970 @ 1100/1650, and 7950 @ 900/1250. was a wee bit faster in benchmarks than dual 7950, so the extra resources of the other card definitely gets used.
     
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  16. Mussels

    Mussels Moderprator Staff Member

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    short version: sometimes the OC will give a performance boost, sometimes it wont, as opposed to single cards, where it always will.
     
  17. abbutec

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    hi all , thx a lot . mucho ideas . think I will do the following:both cards do have a 2.bios integrated, and there i will install the slower ones , 925-1375.
    will stay in touch, byby.
     
  18. abbutec

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    hi folks "THE BEST" , long time pass and my fazit: it was not sattisfightin me : now i will try new project . i get a r9 280x and a hd7970 both by gigabyte .
    i put the r9 in first pci and hd in second ( still saber x79 -2011, 3930 , corsair cx750 , new (4x4) 16gb ram1600 , ccc 13.9 , c:120ssd old sata ).
    read about hypersly - what does it make possible ?
    thx for Your angagement ( interresse ) , and excuse my bad english ( swiss citizen ) .
    ps . for "cadaveca" do u have a bakery sellin mandelbrot - may u send a piece - cool ,byby
     
    Last edited: Jun 30, 2014

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