SLI requirements?

Discussion in 'Videocards - NVIDIA GeForce' started by kam03, Apr 21, 2006.

  1. kam03

    kam03 Guest

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    I have an ASUS 7800 gtx 256mb graphics card and i would like to buy anohter 7800 GTX 256mb graphcis card to do SLI. I would like to know if the 2nd card has to be the same manufacture or can i buy a different manufacture card?

    Thanks
     
  2. KoukiFC3S

    KoukiFC3S Master Guru

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    You can get a different manufacturer card.
     
  3. kam03

    kam03 Guest

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    but they both have to be the same clock speeds? if i was to buy an xfx one with pre oc, do i just underclock to make them both same clock speeds?
     
  4. daveid

    daveid Ancient Guru

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    from my understanding the card in slot 1 determines the default clock speed.
     

  5. KoukiFC3S

    KoukiFC3S Master Guru

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    I believe that it will set the speeds to the card in the first PCI Express slot.

    However I read that it would also downclock both cards to the lower speed one.

    When I went SLI I used identical cards so I'm not too sure about that one.
     
  6. raging_dragon

    raging_dragon Master Guru

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    Yes you can use different manufacturers' cards to SLi with.
    No. The clock speeds will be reverted to the slower of the two cards no matter which PCI-e slot they are placed in.
    Different manufacturers's cards will only work in SLi if you use driver series 8x.xx onwards.
    When overclocking, you overclock both cards as one. If I set the overclock to 465 on the core then both will run at 465. The same goes for the memory too.
     
  7. kam03

    kam03 Guest

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    thanks for the help guys.
     
  8. 7 deadly sins

    7 deadly sins Master Guru

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    i have the same question. Currently i have a EVGA 7900gt CO superclock at stock speeds (550, 1580) and i am loooking to get another 7900gt. However i was looking to get the EVGA 7900GT with a core clock of 500 and memory at 1500mhz. Will this be a problem and wil it be difficult to setup. Will i run at the lower settings or can i oc the slower card to the superclocked levels or do i have to OC them both?

    Thanx in advance
     
  9. 7 deadly sins

    7 deadly sins Master Guru

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    any thoughts
     
  10. AccordTR

    AccordTR Master Guru

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    To answer your question..... yes you can use mixed vendors of THE SAME cards, so two 7800gtx's, regardless of brands will work together. BUT in my opinion and many others too, you should try to MATCH your cards, just like you should always MATCH things like ram. Although mixing will work, bios's often differ and can lead to problems such as heat differences and clock differences, so matching eliminates these possiblities

    As for if the clocks are different, sli will read the first, pci-e one slot, as the default
     

  11. 7 deadly sins

    7 deadly sins Master Guru

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    would it be safe to assume that two evga cards that vary in clock speeds would still have the same bios?
     
  12. AccordTR

    AccordTR Master Guru

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    If the default clocks are different, then the bios's would be different, i assume you are comparing a reference to a KO edition ?
     
  13. 7 deadly sins

    7 deadly sins Master Guru

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    im am comparing the 7900gt CO to the 7900Gt Co superclocked. Would the bios be different even though they are the same minus the clock differences?
     
  14. Grizza

    Grizza Active Member

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  15. AccordTR

    AccordTR Master Guru

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    Yes you'll be fine, i would put the lower clocked card in the first pci-e slot and then overclock from the lower to the higher
     

  16. Harl0ck

    Harl0ck Member

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    GPU:
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    When you have two uneven cards . I.E one runs default at a higher (OC) setting then your other card , putting them in SLI WILL result in your SLI setup using the lower of the two`s clockspeed REGARDLESS of videocard slot position.
    It`s symetric scaling after all , and I have tried this in practice too cause I was solving a different problem on the side .

    So if you buy a slower clocked card , you best be sure that it clocks as high as your current card , if not be prepared to accept that you`ll have to run one of your cards at a lower speed , tough . . with two GPU`s you should still have stellar performance regardless :)

    Whilst i`m on the subject here let me kill another myth .
    Overclocking your PCI-E bus when using SLI to try and increase the bandwidth (i.E unless your running the latest motherboard you`ll have a 16x PCI-E lane shared in 2x8X PCI-E when using SLI ) WONT help you at all .
    I figured I would give that a try but even overclocking the PCI-E bus 30 mhz more ( 100 to 130 ) didn`t give me any FPS , or 3Dmark increases at all , unlike in the good `ol AGP days bumping up the AGP bus 2-3 Mhz ( Thats all you could get usually) gave you a couple of frames more !
     

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