This message indicates that your system is running low on available RAM during the rendering process. When Windows detects insufficient memory, the host software (3ds Max or Cinema 4D) may crash or begin "paging" - a process where data is moved to your hard drive. This will significantly slow down parsing and rendering, even if you are using a high-speed SSD.
To avoid these issues, we recommend closing unnecessary applications and optimizing your scene to reduce memory usage. Example issues and solutions are listed below in this article.
Note: this message refers to RAM, not disk space! Even with hundreds of gigabytes of free disk space, you can still run out of RAM.
The "System is running low on RAM" error message displays a breakdown of various rendering components and their RAM usage. This provides you with information on what exactly should be optimized to lower the RAM usage. The same pop-up window appears regardless if you're using 3dsmax or C4D.
Possible causes and solutions:
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Cause: Too high output resolution.
Solution: Lower the output resolution if possible.
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Cause: Too many render elements.
Solution: Remove any unnecessary render elements (and lower your output resolution if possible).
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Cause: Denoising enabled for render elements.
Solution: Enable denoising only for those render elements where it is absolutely necessary. Denoising each render element requires additional RAM. Denoising multiple render elements can result in high RAM usage - this also applies to LightMix ( 3ds Max | C4D ).
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Cause: Too many high-resolution textures in the scene.
Solution: Reduce the number and resolution of bitmaps used in the scene.
You can also make sure the Automated out-of-core textures option is enabled in Render Setup > System > Performance. This automatically offloads unused parts of textures to disk and can reduce peak memory usage by up to 30%. Note: this works only with Corona Bitmap.
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Cause: Displacement screen size value set too low.
Solution: Do not use very high displacement quality settings unless it's absolutely necessary. Usually, the screen size can be left at the default value. It should never be set to less than 1 pixel. Higher values mean lower quality and lower RAM usage. Regardless if you're using 3dsmax or C4D, you can let the Autobump feature take care of fine detail.
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Cause: Using too detailed displacement maps.
Solution: Use less detailed displacement maps. Let bump take care of fine detail. Autobump does that automatically regardless if you're using 3dsmax or C4D.
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Cause: Too heavy scene geometry.
Solution: Optimize scene geometry if possible and reduce the number of objects. Use instancing whenever possible.
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Cause: The computer has insufficient RAM installed to render the specific scene.
Solution: install more RAM (at least 64 GB is recommended for most "standard" interior and exterior scenes; 32 GB is the bare minimum).
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Cause: Lots of memory-expensive applications running at the time of rendering.
Solution: Close any other applications running on your computer that could take a noticeable amount of memory (Such as Photoshop, compositing software, web browser with many tabs open, etc.)
Additionally, you can enable the "Conserve memory (slow)" option in the Performance tab of the Render Setup window. This will slightly reduce RAM usage but will also slow down rendering by about 5%.
If you're using 3ds Max, you can activate it in Render Setup > Performance > Performance Settings rollout:
Location of the "Conserve memory (slow)" option in 3dsmax.
If you're using C4D, you can activate it in Render Settings > Corona > Performance Settings tab:
Location of the "Conserve memory (slow)" option in C4D.