How to Enable OptiX Ray Tracing in Blender

NVIDIA OptiX hardware acceleration significantly reduces render times in Blender's Cycles engine by utilizing the dedicated RT (Ray Tracing) and Tensor cores found in modern NVIDIA GPUs. This guide covers the prerequisites, step-by-step instructions to enable OptiX for rendering and viewport previews, and tips to configure OptiX-based AI denoising for maximum performance.

Prerequisites

To use OptiX acceleration, you need:

  • An NVIDIA GPU: NVIDIA RTX series (recommended for full hardware RT support) or NVIDIA GTX 900 series and newer (Maxwell architecture and above).
  • The latest NVIDIA graphics drivers installed.
  • Blender 2.81 or newer (latest stable version recommended).

Step 1: Enable OptiX in Blender Preferences

  1. Open Blender.
  2. Go to the top menu and select Edit > Preferences.
  3. In the Preferences window, select the System tab from the left sidebar.
  4. Under the Cycles Render Devices section, click on the OptiX tab.
  5. Check the box next to your NVIDIA GPU.
    • Optional: You can also check your CPU to use hybrid rendering, though GPU-only rendering with OptiX is typically faster.
  6. Close the Preferences window (settings save automatically).

Step 2: Set Cycles to GPU Compute

  1. In the Properties panel on the right, click the Render Properties tab (camera icon).
  2. Set the Render Engine to Cycles.
  3. Under the Device dropdown, select GPU Compute.

Cycles is now configured to utilize hardware-accelerated ray tracing via OptiX for final renders and viewport previews.

Step 3: Enable OptiX Denoising

OptiX includes an AI-accelerated denoiser that cleans up noise rapidly in both real-time viewport rendering and final renders.

  1. Stay in the Render Properties tab and expand the Sampling panel.
  2. Expand the Viewport sub-panel:
    • Check the Denoise box.
    • Set the Denoiser dropdown to OptiX.
  3. Expand the Render sub-panel:
    • Check the Denoise box.
    • Set the Denoiser dropdown to OptiX (or OpenImageDenoise if you prefer sharper high-sample final results).

Summary of Benefits

  • Faster BVH Building and Traversal: Hardware-accelerated bounding volume hierarchy (BVH) reduces pre-render calculation and ray-intersection times.
  • Real-Time Viewport Feedback: OptiX viewport denoising allows you to preview materials, lighting, and reflections interactively with minimal lag.
  • Lower Render Times: Pure ray tracing scenes (reflections, refractions, global illumination) typically render 20% to 50% faster compared to standard CUDA rendering.