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Something i noticed about SLI with gpu-z

Discussion in 'Overclocking & Cooling' started by Solaris17, Feb 16, 2009.

  1. Solaris17

    Solaris17 Creator Solaris Utility DVD

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    SLI is supposed to clock down to the lowest clocked card when enabled. but when i enable both my GX2's gpu-z reports them at their stock clocks. evga percision does the same. i need to manually clock the cards if i want them to run at the same speed. does anyone else find this odd? could it be that their are 2 cards per card sorta speak? and that one GX2 doesnt govern the other but rather 1 GPU per card might govern the slave?
     
  2. W1zzard

    W1zzard Administrator Staff Member

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    or maybe sli doesn't clock down the cards?
     
  3. newtekie1

    newtekie1 Semi-Retired Folder

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    I had something similar.

    I had my two 9800GTX's, and I had a problem with the driver. It was only installing for one of the cards, so the other card was running at some insanely low clock speed.

    When SLi was enabled, GPU-z showed the two different clock speeds for the two cards. However, the SLi performance was extremely low, indicating that SLi was running both cards at the same low clock speeds, even if GPU-z was reporting the one card at the higher clocks.

    So I think that GPU-z and the other programs might still be reading what the card is supposed to run at, even though the card is actually running at something different in SLi.
     
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  4. Solaris17

    Solaris17 Creator Solaris Utility DVD

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    sli is supposed to clock down the cards and nvidia says that to this day.
     
  5. W1zzard

    W1zzard Administrator Staff Member

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    so you should get identical numbers if you run the cards in the "wrong" configuration and if you set the clocks manually to match ? try it
     
  6. Solaris17

    Solaris17 Creator Solaris Utility DVD

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    my perf increses around 300 or so points when i manually oc the cards to match my highest clocked card.
     
  7. W1zzard

    W1zzard Administrator Staff Member

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    you need to clock down to match .. so if performance is the same as unmatched then the clocks are indeed automagically matched by the driver. if it is lower or higher then the driver does not match clocks
     
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