I have a system contains Ryzen 7 2700x 32GB RAM and GTX 1060 3GB. I am rendering a scene and that scene is rendered by CPU in 6~7 minutes. When turn on the PC, all applications are closed and often Graphics card render fine with render time of around 6 ~7 seconds. In rendering my CPU and GPU are very closely matched.

But after 2nd or 3rd frame GPU starts to slow down and it render each tile very slow. And then it takes 35~40 minutes per frame. CPU is fine it renders 6~7 minutes even for 48 hours , CPU render time was consistent. But GPU goes way too slow. THe only solution is to restart the computer and dont open any file just render with blender and some time GPU render for hours in 7 minutes but most of the time from 5th 6th frame onwards GPU slows down dramatically. I have tested my graphics card for other benchmarks and hardware test and i play games on it, its hardware seems fine.

My speculation is that VRAM of GPU is the bottleneck here, which is 3GB? Can any blender expert help me in this regard?

  • $\begingroup$ Hi. You've tagged your question with both the 'cycles-render-engine' tag and the 'blender-internal-render-engine' tag. Which render engine are you using? $\endgroup$ – Ray Mairlot Jul 15 at 22:50
  • $\begingroup$ Cycles engine is the one i m using $\endgroup$ – Muhammad Ahmed Aug 28 at 23:52
  • $\begingroup$ If your scene exceeds the VRAM size then this would explain the slow down. Blender is using the system memory and the memory synchronization with the GPU impacts the performance. See this section of the GPU rendering page in Blender's manual: "With CUDA and OptiX devices, if the GPU memory is full Blender will automatically try to use system memory. This has a performance impact, but will usually still result in a faster render than using CPU rendering." $\endgroup$ – Robert Gützkow Aug 29 at 16:12

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