Will my CPU bottleneck a third GPU?

Discussion in 'Videocards - AMD Radeon' started by Atel, Nov 20, 2009.

  1. Atel

    Atel Member

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    GPU:
    PowercolorHD4870x2 2048MB
    Hi all,

    Running a 4870x2 on a p5q3 deluxe mobo. CPU is a currently stock clocked Q9550.

    I believe that the mobo has dual x16 PCI-E lanes, (can someone verify?) and I am contemplating adding a 4870 to the setup for tri-fire.

    Can anyone reliably estimate, or point me to some charts and graphs, whether I will get much real-world improvement, or whether the system is already bottlenecked elsewhere?

    Many thanks in advance.
     
  2. Zebatshu

    Zebatshu Member Guru

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    GPU:
    EVGA GTX670
    Well with 2 4850's my CPU (same as yours) is already hitting 70% in many titles. So with a 4870x2 i can only imagine you are almost at its limit. IMO monitor your CPU usage atm and if its already high, 90% ish then it would be of no use to slam in a 3rd GPU if your not going to OC this CPU.

    Edit: Another thing to take into consideration is the fact that you will lose 50% of the main cards memory if you crossfire it with another card, assuming the 4870 will have 1GB. Can some one just verify but i think this might hurt you on big resolutions, and thus you will not really see a big improvement even if the cpu not bottlenecking the cards.
     
    Last edited: Nov 20, 2009
  3. DSK

    DSK Banned

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    GPU:
    HD5770/BenQ G2220HD
    what res do you play at?

    Also Tri is hit and miss sometimes games just wount run it.
     
  4. Sever

    Sever Ancient Guru

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    not quite true. the 4870x2 card is read as two separate 1gb cards as the gpus are allocated 1gb each.

    so he will not lose 50% of his main cards memory as each gpu is read as 1gb to begin with.
     

  5. Atel

    Atel Member

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    Good thinking Zebatshu - sometimes you just need someone to point out the obvious for you :)
    Meanwhile - yeah, I have the 2gb x2, and would get a 1gb 4870 and so each gpu would still have 1gb.

    klyzer - my vdu is natively 1920x1200 and looks horrible at 1650. There are some titles that are beginning to labour a little with the x2 at 1920x1200, so I'm just considering my options for getting more mileage out of this system for as little money as possible.
     
  6. jmpnop

    jmpnop Maha Guru

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    Honestly you won't see a big difference. You should now look forward to Core i7..
     
  7. Zebatshu

    Zebatshu Member Guru

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    GPU:
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    LOL i completely forgot the X2 GPU's have 1GB each, silly of me. Well in that case an extra card wont help you much. Only a i7 or a decent OC quad will be able to help you here.
     
  8. ibitato

    ibitato Ancient Guru

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    GPU:
    4870X2+4870 1GB on S T260
    from my experience, at 1920x1200 you need at least 3.6Ghz on the quad.
     

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