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Rendering with two gpu, third gpu for display, different memory usage on gpus

ps2000ps2000 Posts: 278
in The Commons

Hello,

I have three graphic cards in my system, a GTX 1070 and GTX 960 for rendering and a gt 710 for the display. 

Recently I checked the memory usage of the two rendering gpus with gpu-z while rendering. I was astonished that the scene needed 6288MB on my gtx 1070 while only using 3643 MB on my GTX 960. Both cards were obviously rendering the scene (see gpu-z screenshots). And according to my understanding the GTX 960 wouldn't start rendering the scene if the memory on the card was not enough for the scene. 

As mentioned in the headline the smallest card is used for the display (GT 710). So both gpus should be able to use their full memory for rendering.

What's going on here?

Has someone the same problem?

gtx10702.PNG
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gtx9602.PNG
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gt710.PNG
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Comments

  • ps2000ps2000 Posts: 278
    edited April 2020

    It gets stranger.

    After the render finished the memory on the gtx1070 didn't clear completely. Nearly 3000MB are still used while the memory on the GTX 960 got nearly completely cleared.

    Naturally I closed the window it rendered to.

    gtx9603.PNG
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    gtx10703.PNG
    391 x 519 - 25K
    Post edited by ps2000 on
  • Richard HaseltineRichard Haseltine Posts: 107,953

    Are you sure something else isn't using some space on the 1070?

  • ps2000ps2000 Posts: 278

    I am pretty sure. Before I start the render process the memory usage of the GTX 1070 is at 90MB and 45 MB on the GTX 960

  • Richard HaseltineRichard Haseltine Posts: 107,953

    Had you used it for a dForce simulation? That should release any memry used, of coruse, but if not it is limited to one device.

  • ps2000ps2000 Posts: 278
    edited April 2020

    No dForce simulation. It's strange. Shouldn't the memory usage be the same on both rendering cards?

    Before I built in the GT710 I also had the phenomen that more memory on the GTX 1070 was used than the GTX960. But I thought that was because the display was conncected to the GTX 1070. 

    That was the reason why I bought the GT 710 because I thought then I could use the full 8GB of the GTX 1070 for rendering. 

    Maybe someone with two gpus can check if he has the same phenomen?

    I think it should be of interest for everyone who renders with two gpus if the memory of the first one ist not correctly used.

    I also noted that I posted a wrong screenshot in my second post for the GTX 1070. I corrected that. The screenshot shows now the memory that is still used on the GTX 1070 after the render (2856 MB). You can now clearly see that the used memory drops from 6288 MB to 2856 MB but the memory is not completely cleared. 

    Post edited by ps2000 on
  • outrider42outrider42 Posts: 3,679
    I have 2 1080tis, and the one driving the monitor doesn't even keep that much more data on it than the other. Its like 2gb at most. More often its only about 1gb to 1.5. My monitor is at 1440p.

    Wasn't there an issue with certain versions of Daz not properly clearing VRAM? People who were doing multiple renders in a row were finding it would fall to CPU because of this.

    You could try the beta and see if it does the same thing.
  • ps2000ps2000 Posts: 278

    Thanks

    My Daz-Studio is 4.12.0.86. That's the latest non-beta  version I think.

    Maybe I will try the beta.

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