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    Power Consumption GTX 860m Kepler vs Maxwell

    Discussion in 'Hardware Components and Aftermarket Upgrades' started by refllect, Jul 20, 2014.

  1. refllect

    refllect Notebook Consultant

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    How much more efficient is Maxwell? Will these differences carry over to the GTX 870mx also?
     
    refllect, Jul 20, 2014
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  2. octiceps

    octiceps Nimrod

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    Almost twice.

    Yes.
     
    octiceps, Jul 20, 2014
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  3. HTWingNut

    HTWingNut Potato

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    860m Maxwell is about 50W TDP, Kepler is about 75W TDP, so about 50% increase.
     
    HTWingNut, Jul 20, 2014
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  4. octiceps

    octiceps Nimrod

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    But Maxwell 860M is faster.
     
    octiceps, Jul 20, 2014
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  5. HTWingNut

    HTWingNut Potato

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    True, by about 10%. But I still wouldn't say double TDP.
     
    HTWingNut, Jul 21, 2014
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  6. Marksman30k

    Marksman30k Notebook Deity

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    IPC wise, a 128 Maxwell CUDA SMM can deliver 90% the performance of a 192 Kepler CUDA SMX due to improvements to the scheduling efficiency. This means that the CUDA Maxwell unit is 40% faster at the same clock speed. Considering the TDP of Maxwell is also 50% less than Kepler. This is where the double performance per watt figure comes from.
    Another way to look at it is a 640 core Maxwell SKU is equivalent to a 896 core Kepler SKU. Also take in to consideration that Maxwell can also be clocked higher due to the lower starting TDP.
     
    Marksman30k, Jul 21, 2014
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  7. refllect

    refllect Notebook Consultant

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    But real world tests don't seem to indicate this at least from what I've read the Maxwell 860 is drawing almost as much as the Kepler 860
     
    refllect, Jul 21, 2014
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  8. octiceps

    octiceps Nimrod

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    They measured power draw directly on MXM slot/mobo? o_O
     
    octiceps, Jul 21, 2014
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  9. refllect

    refllect Notebook Consultant

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    refllect, Jul 21, 2014
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  10. octiceps

    octiceps Nimrod

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    octiceps, Jul 21, 2014
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  11. refllect

    refllect Notebook Consultant

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    Contrary to our expectations, both GPUs are very similar in regard to the power consumption. 88-110 Watts of the Schenker W504 in the first scene of 3DMark06 is barely more than the Schenker XMG A504 with the identical Core i7-4700MQ CPU (83-107 Watts). Both devices consume up to 150 Watts under maximum load.

    We were even able to determine slightly lower values of the Schenker W504 during idle (13-23 vs. 16-26 Watts). One reason for that should be the additional hard drive of the XMG A504. We did not compare the temperatures and the system noise due to the huge differences of the two barebones.

    They have identical CPUs and I don't think screens and HDDs will create a huge difference in power draw. You can infer that power draw from both GPUs is similar.
     
    refllect, Jul 21, 2014
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  12. Marksman30k

    Marksman30k Notebook Deity

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    I'm going by the figures on Anandtech for the desktop parts. I guess for the notebook space, they didn't really down clock Maxwell and instead to use more of the TDP advatange to improve performance, thus similar power consumption.
     
    Marksman30k, Jul 22, 2014
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  13. nipsen

    nipsen Notebook Ditty

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    ...Anandtech got something right? Weirdest thing I've heard of in a while.

    But it's not as linear as people make it out to be. The major..if you can call it that.. differences between maxwell and kepler is that maxwell can make better use of the dynamic downclocking, and maintain better output on lower clock-speeds. I.e., the kepler functions are slightly better (giving it lower idle/low-burn power drap), and it ends up at similar performance at peak with slightly lower power-draw.

    The idea that it's half the power-draw is bonk, though. That's the normal anandtech reading of whitepapers: "Hoi, I see a number from two different contexts that tell me exactly what the advertisement says! It must be right, let's write that down in 6000 words!".
     
    nipsen, Jul 22, 2014
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