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Explain SLi for me please.

By tastegw
Jan 10, 2008
  1. ok, let me start with this.
    i know what sli is, connecting to video cards with a bridge.
    but my question is, what specs from the 2nd video card are being used when in SLi mode?

    specs i can think of off the top of my head, just tell me if its used or not and explain if needed an explanation.

    *Memory size i was told this does not double when in sli

    *Memory clock

    *GPU core clock

    *shader clock

    *memory bandwidth

    *memory interface

    *stream prossecors

    *RAMDAC


    Thats all the specs i can think of, if i missed any that are utilized thru sli, post them here.

    im also making another post about video cards in general and what specs mean more than others when it comes to performance.

    thanks for any support.
     
  2. MetalX

    MetalX TechSpot Chancellor Posts: 1,388

    Effective memory size doubles.
    Memory clock remains the same.
    GPU clock remains the same.
    Shader clock remains the same.
    Memory bandwidth remains the same.
    Memory interface remains the same.
    Stream processors double.
    RAMDAC remains the same.

    While that list may make it look like SLI doesn't offer a significant performance increase, that's not true.

    While many of those things (especially those involving clock and bandwidth) do not increase, there are now twice as many of those things working at the specified clock/bandwidth, all focused on rendering your game.

    Performance gain from single card to SLI is about 75-80%, with high-end cards. Might be different with mid-range and entry-level cards.
     
  3. tastegw

    tastegw TS Enthusiast Topic Starter Posts: 188

    thanks, was reading at another random place, and one guy said this

    "sli mode, why pay 200% to get 120% performance"

    this is what caused me to post here about sli,

    anything over 50% sounds pretty good to me when pushing high end cards.

    200+ stream proccesors sounds good to me even tho i dont know exactly what they do ;) lol.

    so effective memory size , is this the MHz part or the mb part?
     
  4. ShipMaster

    ShipMaster TS Rookie Posts: 70

  5. MetalX

    MetalX TechSpot Chancellor Posts: 1,388

    None of the clock speeds or bandwidths change when going from single card to SLI. What does change is this:

    The number of GPU cores doubles.
    The number of Stream Processors doubles.
    The amount of memory (in MB) doubles.
     
  6. tastegw

    tastegw TS Enthusiast Topic Starter Posts: 188


    thanks a bunch metal and ship.

    after reading at the sli site, they say you can get up to a full 200% with two cards under high resolution and certain applications.

    sounds good to me.
     
  7. ShipMaster

    ShipMaster TS Rookie Posts: 70

    I'm glad that I could help.
     
  8. MetalX

    MetalX TechSpot Chancellor Posts: 1,388

    No problem.
     
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