Power for GPUs, finally some real numbers !

Discussion in 'Mac Pro' started by MacVidCards, Aug 27, 2013.

  1. MacVidCards Suspended

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    #1
    I realized that "Hardware Monitor" offered the ability to read power draw from PCIE slots and the Booster cables. Unfortunately, you need to get the paid version to do this, but for $10...why not?

    My testing of GTX780 EFI cards has found them stable in MP using existing power while running Titan on existing power can do a violent shut down if you try to run "FurMark"

    I wanted to put some numbers on this and this software offered a chance to find out some actual answers.

    It seems that 3,1 MP reports higher current draw then 4,1/5,1, but I will start with the 3,1 numbers. You may wish to send your children from the room, these numbers are alarming.

    I am going to start the thread with a comparison of GTX780 with GTX570 2.5GB. The GTX570 is a well loved card that many use in their MP. I do not know of ANYONE reporting power issues with them, whether EFI flashed or running using the self0 initing drivers. I ran a bunch of recent Nvidia cards through the After Effects benchmark on this board and found that the GTX570 is equal to the new GTX680 for that test.

    I also decided to use that render as one of my test points for power draw.

    GTX570 AE render 161 Watts
    GTX570 Furmark 250 Watts
    GTX780 AE render 169 Watts
    GTX780 Furmark 230 Watts

    In the Windows world, the Fermi cards got a special driver tweak that limited current draw specifically for Furmark. I'm guess that OSX didn't get this tweak.

    Interestingly, it is possible to get 3,1 to shut down by running the Furmark benchmark at a high resolution. Same res on GTX780 will complete test.

    I will do same tests on 4,1/5,1 and post those numbers, but I am curious if anyone else with a 570 could. With a 580 would also be interesting.

    Please note that the software has PCIE Lane & Boost values switched.
     

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  2. RoastingPig macrumors 68000

    RoastingPig

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  3. Tesselator, Aug 27, 2013
    Last edited: Aug 30, 2013

    Tesselator macrumors 601

    Tesselator

    Joined:
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    #3
    Nice numbers, thanks! My paid version of Hardware Monitor reveals the same numbers on the GTX 570 for the GTX570 AE render as you posted (160W) - FurMark goes up around what you posted as well but I didn't make a note of it so I dunno exactly (somewhere between 240W and 300W IIRC). Also my GTX 570 is 1.28GB and not the 2.5GB version so it looks like there's almost no difference between the 1.25GB and the 2.5GB cards.
     
  4. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #4
    This is incredible

    Why did we not have this during that really long argumentative thread about whether or not the AMD 7970 would blow up traces?

    Now I wish someone with a 7970 would get this and report back. Not that I really care because I've settled on a 680, but just to finally answer the question and satisfy curiosity.
     
  5. MacVidCards thread starter Suspended

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    #5
    Ask, and you shall receive.

    So, Render Load 145 Watts
    Furmark Load 237 Watts


    A couple notes:

    1. I was unable to run Furmark in full screen with 7970, it knocks 3,1 out instantly. (GTX780 doesn't do this)

    2. I ran it in a small Window to get these numbers.

    3. I can't do the "Ray Trace Render" in CS6 since AMD cards are unable to run it.

    4. Instead I ran Luxmark OpenCl test to get Render stress levels.

    5. This is on a regular 7970, not the "Ghz Edition" which was AMD's effort to play catch up to GTX680. So a "Ghz Edition" will likely have higher numbers. Since regular one is already hitting 150 watts on one connector, I wouldn't run Furmark on a 7970 for long.
     

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  6. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #6
    Thanks!

    If I understand these images correctly:
    • "Slot 1" refers to the PCIe slot for the 7970.
    • "Slot 1 Boost" and "Slot 2 Boost" refer to the supplementary power cables?
    • "Slot 2" is some other card and not relevant.
    (I looked at the HW Monitor documentation, but couldn't find an explanation.)

    Anyway, if my understanding is correct, then the cables are actually extremely underutilized but the card is pulling way too much from the PCIe slot itself.

    I know some people had the theory that it was fine because the card would pull perfectly evenly from all three sources, which seemed a little too much like wishful thinking.
     
  7. MacVidCards thread starter Suspended

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    #7
    Actually, the guy has the labels switched

    No other cards are present.

    It is pulling 143 Watts from the 6 pin connector that is connected to 8 pin plug on card.

    But keep in mind that Furmark is basically a "worse than worse case scenario"

    I do not believe that you could use any legit piece of software and pull that amount of juice.

    Next I should drag 4 monitors together and see how much more current is drawn.
     
  8. Tesselator macrumors 601

    Tesselator

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    #8
    I tend to agree. I think to draw the same as furmark one would have to run a game or two (like WitcherII) and also attempt to edit video at the same time or something like that - all on different monitors of course.

    That furmark is wicked!
     

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