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Iray render uses cpu only after a few renders.

garlicpeppergarlicpepper Posts: 6
in New Users

Hello I recently bought a Nvidia 970 card to use solely for renders. I also have a 770 but when I render I set it so Daz3d uses the 970 only. Usually this works very well and the render goes fast while not interupting other computer use. After a few times though the render slows down as if I was cpu only. I checked task manager and usually a render with 970 only takes about 50% of the cpu. After a few times the render slows down to about 5% of the speed and the cpu is at 100%. This leads me to believe that daz3d chose not use my video card but my cpu instead. If I close and re open daz3d it renders fast again. Any idea what could be causing this?

Comments

  • mjc1016mjc1016 Posts: 15,001

    Are you rendering direct to file or to a new window?

    If to a new window are you actually closing each one, once it is finished?

    If you are not actually closing the render window after each one finishes, then yes you could be running out of memory on the card and falling back to CPU only.  Iray will only use the GPU if the scene can fit into the card's memory and leaving the render window open will keep some memory reserved, in case you want to resume the render.  So, after several renders, you will probably have enough memory 'reserved' to make the card not have enough room for the scene.

  • garlicpeppergarlicpepper Posts: 6

    Ah yes I've been doing render to window. I do sometimes leave them open. I'm not sure if I've had windows open every time though. I'll be more careful in the future and see if it helps, thanks.

  • ToborTobor Posts: 2,300
    garlicpepper said:

    This leads me to believe that daz3d chose not use my video card but my cpu instead. If I close and re open daz3d it renders fast again. Any idea what could be causing this?

    Rather than guessing, review the log after the render to see what actually happened: Help->Troubleshooting->View Log File. In many cases, a reason (though sometimes cryptic) is provided. That can give valuable clues.

  • LayLo 3DLayLo 3D Posts: 329

    This is a known problem, I've chatted to tech support about it. When it happens you have to close Daz Studio and re open it to clear your VRAM. Closing the Render Window after renders/partial renders will help, but it seems to still happen eventually.

  • KhoryKhory Posts: 3,854

    I get kicked to cpu only if I stop/close a render before there is any visable image. It does not happen if I am patient enough to wait for that first image though. Once it kicks me to cpu I have to restart the computer to get GPU back.

  • LayLo 3DLayLo 3D Posts: 329
    Khory said:

    I get kicked to cpu only if I stop/close a render before there is any visable image. It does not happen if I am patient enough to wait for that first image though. Once it kicks me to cpu I have to restart the computer to get GPU back.

    Restarting the program doesn't do the trick for you?

  • KhoryKhory Posts: 3,854

    Not so much no. I think it is a penatly imposed on me for being so impatient.

  • ToborTobor Posts: 2,300

    A common cause of the kickout is a damaged scene database, which apparently can happen (among other reasons) when a JIT material conversion produces the wrong result. When restarting D|S doesn't work, I'm guessing to clear out any scene database junk, a full reboot is otherwise necessary. I've had to do the latter sometimes when using a converted V4 texture set that was munging up the works. Just quitting and restarting D|S didn't solve it.

  • mjc1016mjc1016 Posts: 15,001
    Tobor said:

    A common cause of the kickout is a damaged scene database, which apparently can happen (among other reasons) when a JIT material conversion produces the wrong result. When restarting D|S doesn't work, I'm guessing to clear out any scene database junk, a full reboot is otherwise necessary. I've had to do the latter sometimes when using a converted V4 texture set that was munging up the works. Just quitting and restarting D|S didn't solve it.

    One more reason to make sure all materials are pre-converted before rendering.

  • ToborTobor Posts: 2,300

    Yeah, and would be great if Daz or some enterprising PA would create a script for looking for non-Iray surfaces. Took me ages to eventually locate the problem. 

  • kliewerkliewer Posts: 0

    Hello everybody,

    as I can see from your comments, you guys have good knowledge concerning Iray and cpu/gpu usage.
    I have some problems with rendering an architectural scene:

    Due to the big amount of grass, I divided that scene into four regions which are rendered separately - one after the other. Each time I render a region grass is deactivated outside the region. The reason is saving RAM, because it is limited to 16 GB. The first three regions haven't been a problem, so approximately 75% of the final picture are good and without noise. CPU and GPU ran fine and I saved the picture-parts after ca. 12 hours.

    When rendering the last part, cpu starts as usually. After ca. 10 minutes CPU goes down from 90-100% to ca. 15%. The gpu is also down to 15-20%, although 11 of 16 gb RAM are used.
    When continue rendering the picture it does not improve (i don't see any changes) and there is a lot of noise after 12 hours. It is not comparable to the other three parts, which were made in the same way. I did not change any setting in Iray or in windows.

    I don't understand that result. Do you have any clue, why cpu is going down and gpu is quiet low at the beginning?

    Intel (R) Core (TM) i7-4770K CPU @3.50 GHZ, GEFORCE GTX 680 4 GB RAM, 16 GB RAM

    best regards
    Eduard

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