Why sometimes GPU not working as fast as it should?
James
Posts: 1,025
My GPU load is 100% but the speed is very slow. 4070ti
Like if a scene 2 mins to render at full speed, it can sometimes become 3-4 times slower.
The GPU temp also doesnt raise up.
Why?
Post edited by James on
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Is it the same scene that somettimes is slower?
Then, what does your log say, in terms of iterations and convergence?
We need more information. Presumably you are not rendering the exact same scene over and over and so what is different between them? There are several things you can change in your scene which will make the render take longer or shorter. Also, check your logs as felis has said, it might be that the scene is too much for the VRAM and so it's dropping to CPU rendering. Note, even if you ARE rendering the same scene more than once, it can still be the case that the first time it all fit on the VRAM on your graphics card and the second time it will not. This is the reason why many people say the best thing is to quit Daz Studio after finishing your scene and then re-load it before doing the render.
The difference... is angle.
I don't think the scene is too much for Vram.
Mine just go black, if not enough vram.
I don't use CPU for fallback.
Using most of the vram, yes.
What to look in the log?
The log is Help > Troubleshooting > View Log File.
In the log you can see how the image progress in terms of convergence.
In a new angle there might be an area that isn't well lit, or there is many reflections, and therefore take more iterations to converge.
I mean what word to look in the log file.
Is it:
2023-09-19 19:19:14.004 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Using no convergence estimate.
You should have a large section in the log while it renders. That lists which iteration is has done, and once in a while the convergence value.
Then you can compare the 2 renders in terms of how many iterations are done, and how fast the convergence value increased.
If angle is the issue, I'm guessing that the lighting is the cause.