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IRAY GPU (RTX A4000) rendering waay slower than CPU (R7 3700)

boronk_223d50468cboronk_223d50468c Posts: 7
in The Commons

Hi,

I have set up a scene with the MMX Rain Prop and 3 lights and as soon as I make the raindrops visible, the GPU (CUDA) renderer slows down to 1/3 of the CPU renderer. I am really confused now because I read a lot and all said, GPU is always waaay better than CPU.

Now to be sure my setup is not broken, I did some other tests with a more vanilla setup and also the raindrops invisible. This turned the speed differences around to make the GPU again faster than the CPU.

Is such behavior normal or expected? Or are there any flags the IRAY renderer ignores once it falls back to CPU?

At a first sight, the results look the same.

Christian

Comments

  • PaintboxPaintbox Posts: 1,633

    If your scene exceeds the VRAM on your card, it drops to CPU. So check if reducing the memory requirements of your scene helps. Tools like Scene Optimizer (textures) or even Decimator (polygons) can help. Usually it's the textures that count heavy to VRAM usage.

  • boronk_223d50468cboronk_223d50468c Posts: 7

    Oh, no it didnt drop to CPU. I did also try the following combination

    GPU only (slowest)

    CPU only (faster)

    GPU+CPU (fastest)

    I als did re-inspect the renderers at 20 iterations, and there is in fact really visual difference between CPU and GPU. The CPU looks brighter in the semi transparent rain parts. So I would guess, they do not calculate the same things.

    Christian

     

     

  • nakamuram002nakamuram002 Posts: 793

    Have you updated your driver to the latest version?  

  • rrwardrrward Posts: 556

    I just dropped an RTX A5000 in my system and it is as fast as the two 2080ti's it replaced. If you upgraded from a GeForce card make sure to remove the GeForce drivers and install the Quadro drivers as the A4000 can't use GeForce drivers.

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