: Other open programs (like Chrome, Substance Painter, or Photoshop) are "stealing" VRAM that the renderer needs. Complex Features
Every "Render Element" (like LightMix or Z-Depth) requires its own memory buffer. Delete any that aren't essential for your final composite. Summary Table: VRAM vs. Performance Probable Cause Recommendation Warning appears, render is fast Tight VRAM but manageable Ignore the message. Warning appears, render is very slow Frequent memory swapping Optimize textures/geometry . Warning followed by "Illegal Address" Total VRAM exhaustion Reduce scene complexity or switch to CPU.
If you have integrated graphics (iGPU) and a discrete GPU (dGPU), force the renderer to use only the discrete GPU. The iGPU often has very limited memory (512MB–2GB), triggering the warning. In Blender: – disable the iGPU in CUDA/OptiX/HIP devices list.
Are you seeing this warning on a specific scene, or does it happen even with a ?
If you have access to the rendering settings (e.g., in a custom script or application), reduce the requested samples per thread to . Ironically, matching the cap avoids the warning and the overhead of automatic reduction. : Other open programs (like Chrome, Substance Painter,
The warning " Num samples per thread reduced to 32768, rendering might be slower " is a critical notification typically found in or other CUDA/RTX-based rendering logs. It
In most other cases, you can safely ignore the message. Many production studios render with this warning every day without noticeable downside. However, if you are rendering animations with hundreds of frames, a 10% slowdown adds up – that’s when you should apply the fixes above.
to track your exact VRAM usage in real-time. If it's constantly at 100%, your hardware may be underpowered for the scene. Use Out-of-Core Features
signals: void configChanged(); void warningTriggered(QString message); Summary Table: VRAM vs
: Keeping a web browser (which can use ~1GB of VRAM) or other 3D software open while rendering. How to Resolve It
You can monitor your actual memory consumption during the render using a tool like
Let’s be clear: . It is the rendering engine adapting to constraints. You should worry only if:
Go to your Octane Kernel settings and try these adjustments: Warning followed by "Illegal Address" Total VRAM exhaustion
You may also encounter these similar messages:
If you have two GPUs, use one for your monitors and the other strictly for rendering. This prevents the OS and viewport from taking up VRAM needed by the engine.
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