V-Ray Tip: V-Ray Hybrid Rendering Best Practices (CPU+GPU)

Hybrid rendering (CPU+GPU) in V-Ray can shorten iterations and unlock extra throughput—when enabled and tuned appropriately.

• When to use it
  • Great on workstations with 1–2 mid-range GPUs: the CPU adds meaningful rays without starving the GPU.
  • Excellent on laptops or mobile rigs where the CPU is strong but the GPU is limited.
  • Useful on render nodes that lack GPUs: with Hybrid enabled, CPU-only machines can contribute to V-Ray GPU jobs.
• When to skip it
  • On multi-GPU monsters (e.g., 3–4 high-end RTX cards), CPU participation can add sync overhead with minimal gain—test both ways.
  • If you must use the RTX engine (OptiX), note that Hybrid CPU participation is tied to the CUDA engine. For CPU help, render with V-Ray GPU in CUDA mode.
  • Hybrid will not increase VRAM; large textures/geometry still need to fit GPU memory (or rely on out-of-core, with a potential performance impact).
• How to enable it (host-agnostic workflow)
  • Switch renderer to V-Ray GPU.
  • Set Engine to CUDA if you want CPU+GPU Hybrid.
  • Open Render Devices and check your GPUs and CPU (Hybrid).
  • Start with Progressive for look-dev; switch to Buckets for finals if your pipeline prefers bucket-based consistency or memory behavior.
• Practical tuning tips
  • Reserve some CPU for the DCC: if your host feels sluggish, reduce CPU threads for rendering (host/OS affinity) so UI and scene updates stay responsive.
  • Watch thermals and power: Hybrid pushes the full system. Ensure adequate cooling to avoid GPU or CPU throttling.
  • Profile per scene: run a 2–3 minute Progressive render with and without the CPU enabled and compare VFB render time and noise levels at a fixed Noise Threshold.
  • If the CPU is much slower than your GPU stack, you may see negligible gains; disable CPU to reduce scheduling overhead.
• Distributed and farm workflows
  • V-Ray Swarm/DR: enable CPU on each node’s V-Ray GPU device list so CPU-only nodes can join GPU jobs.
  • Keep versions aligned (V-Ray, drivers, plugins) across nodes for consistent sampling and output.
  • Use the same bucket/progressive mode across all machines to avoid mismatched behavior.
• Quality and stability
  • Hybrid maintains V-Ray GPU’s path-traced quality; it does not alter shading models or BRDF energy conservation.
  • Use the V-Ray Denoiser (OIDN/NVIDIA) to consolidate the time saved by Hybrid and lower your sample targets further.
  • Validate final frames against a GPU-only baseline to ensure identical look and noise distribution for approvals.

Pro tip: build two render presets—GPU-only (RTX or CUDA) and Hybrid (CUDA + CPU). A/B test per job and lock the faster preset for the duration of the project.

Need licensing guidance, workstation recommendations, or upgrades for a Hybrid-ready setup? Talk to NOVEDGE, or browse Chaos offerings at NOVEDGE to match V-Ray versions, nodes, and hardware with your pipeline.

You can find all the V-Ray products on the NOVEDGE web site at this page.