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Bottleneck

Discussion in 'AMD / ATI' started by Richard Shepherdson, Nov 16, 2009.

  1. Richard Shepherdson New Member

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    I hear a lot on these forums of CPUs bottlenecking the GPU.

    Has anyone done any tests on this, or any chance of some guidance on what I could move up to without having a CPU bottleneck problem.

    CPU is E6400 @3.344
    Current GPU HD4770 @ 850/1050
    Resolution 22" 1600-1200 don't know if this matters.

    Thanks for all and any advice. :)
    Last edited: Nov 16, 2009
  2. dr emulator (madmax)

    dr emulator (madmax)

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    what's your memory and timings as well?, although maybe not as important
  3. Richard Shepherdson New Member

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    Mem 4Gig (2x2Gb) Crucial Balistix 3,3,3,12

    @836
    Last edited: Nov 16, 2009
  4. dr emulator (madmax)

    dr emulator (madmax)

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    memory looks ok although you haven't said what your thinking of upgrading to :confused:
    also a consideration is your psu, as the larger the gpu the bigger your psu needs to be:)


    update.gif i agree with razaron that you should be able to move upto a 4870
    but the above still applies:)
    Last edited: Nov 16, 2009
  5. razaron

    razaron

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    you should be able to move up to about a 4870 or maybe higher, cause of the overclock on you processor. above 3ghz and your safe <<thats for quad core so im not entirely sure but im fairly sure its the processor clock that brings about the bottleneck (mostly)
  6. qamulek

    qamulek New Member

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    An easy test is to start down/over clocking your cpu and see how it affects performance in games. If its a large bottleneck you should see a decent change in performance by down/over clocking. How much of a change? I don't know, but I imagine the delta-performance per delta-cpu-clock(dp/dc) will be related to how bottlenecked the system is for a particular app. A large bottleneck *shoud* show a large dp/dc in comparison to a system with a small bottleneck, while a cpu which is not bottlenecked in a game *should* show absolutely no gains in overclocking.

    You could try predict when a certain gpu becomes the main bottleneck by graphing performance vs the clock speed of the cpu. You can guess that most processors won't get above 4Ghz per core, and since you can use your cpu to create data up to 3.344 Ghz(relevant to your cpu architecture) you can try extrapolate the performance gains if it were possible to overclock your 3.344Ghz processor even faster(or replace with a faster chip of same type). I imagine this graph should show diminishing returns to just overclocking the cpu more, and at some point you decide that overclocking the cpu more doesn't make sense since you are limited by the gpu. If you find that the gpu bottleneck occurs a decent margin past your max overclock then buy a better cpu, otherwise buy a better gpu.

    The bottleneck test will be very dependent on which game you use for the test, so test with whichever game you want to play with decent performance.

    This is just raw performance though and doesn't represent the actual performance of the system. I imagine more cache/ram/timings(as dr emulator (madmax) mentions)/??? can help make a system have a higher minimum fps then another system even though they both have the same average fps.
    Richard Shepherdson says thanks.
  7. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    One variable failed to mention: resolution you game at versus your max resolution for your display. The higher your resolution, the less your gpu becomes more cpu bound. IMHO, any modern dual core (C2D / Athlon) @ 3.2Ghz and above will not bottleneck a gpu as much as one thinks.
  8. Zubasa

    Zubasa

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    I all depends on the game, some games uses the CPU much more than other.
    While other games it is the GPU that matters.
    For example Star Wars: The Force Unleashed is very demanding on the CPU because it uses the CPU for Havok physics.

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