Warning Num Samples Per Thread Reduced To 32768 Rendering Might Be Slower Online

Lowering the Light Cache settings can free up memory.

Your scene might be hitting the limit of your graphics card memory, forcing the renderer to re-balance its workload.

Limit the number of extra render passes (like AO, shadows, or reflections) you are outputting at once.

If the warning is accompanied by viewport freezing or frequent driver crashes, your operating system is cutting off the GPU too quickly. You can manually extend this window. Press Win + R , type regedit , and hit Enter. Lowering the Light Cache settings can free up memory

On some Intel CPUs, AVX-512 reduces the maximum sample count due to thermal throttling. As a temporary workaround, disable AVX-512 via environment variable before launching your app:

Here is a comprehensive guide to understanding, fixing, and optimizing this issue. What Does the Warning Mean?

Let’s look at typical user actions that trigger the warning. If the warning is accompanied by viewport freezing

Set a (0.01 is standard; 0.005 for ultra-clean prints).

: Rendering in 4K or higher requires significant memory for image buffers.

: Close other GPU-heavy software like Substance Painter, Photoshop, or Chrome to free up memory for your renderer. SketchUp Community On some Intel CPUs, AVX-512 reduces the maximum

If using HDRI lighting, make sure to enable Light Portals to help the renderer calculate efficient light paths.

| Warning / Error | Meaning | |----------------|---------| | Out of GPU memory, falling back to CPU | Severe VRAM shortage. | | Render tile too large, splitting | Same root cause as our warning. | | Kernel failed to launch: invalid resource size | Driver rejecting per‑thread buffer size. | | CUDA error: launch timeout | Different issue, but often related to large work loads. |

When a renderer tries to process a scene, it attempts to load all necessary data—geometry, textures, and displacement maps—into the GPU's video memory. If the scene is too complex for the available VRAM:

This warning typically appears when using (like Blender, Unreal Engine, certain video editors, or 3D renderers) that relies on multithreaded processing.