The code base for V-Ray GPU differs from the code base for the CPU engine. The GPU code base is optimized for GPU hardware and supports a subset of the features of CPU rendering. For a complete list of supported features, please see the V-Ray GPU Supported Features page.
Yes. There are instructions how to do that in the GPU Setup section.
Why isn't my GPU device(s) listed?
Check the list of devices in the GPU Devices list accessed via the ⋮ button next to the GPU Engine button in the Asset Editor's Settings tab. If you don't see your device on the list there (the list is empty), please check whether it is supported.
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V-Ray will display a warning if the GPU used for monitoring is participating in the rendering process.
If you use many GPUs in DR nodes you may find that the network can become a bottleneck at some point, since the GPUs are producing data very fast. Increasing "Max Trace Depth" / "Max Ray Intensity" increases the size of the workload chunks that are being given to the DR nodes and helps reduce the communication between the client and the servers (you can try something like 192/32 or 256/64).
You can use free 3rd party tools like MSI Afterburner and EVGA Precision to monitor both GPU memory usage and utilization. V-Ray GPU also reports how much memory it uses for textures/geometry/light cache/etc in the V-Ray Progress log accessible via a button at the bottom-right corner of the VFB.
Yes, but within its limitations.
What are the differences between Interactive and Production mode?
You can set V-Ray GPU as production renderer by selecting the GPU engine from the Render rollout of the Asset Editor's Settings tab and disabling the Interactive toggle.
The main differences between Interactive and Production rendering is that Production allows you to render animations, and automatically save the render output after the process has finished, while Interactive rendering does not. Once the final noise threshold is reached in Interactive rendering, the process will remain active awaiting further changes to the scene. Manually stopping the render process does not produce automatically an image written to disk.
Another difference is that in Production mode V-Ray will calculate and use Light Cache for GPU GI calculations if it has been set as secondary GI engine. In Interactive mode V-Ray GPU always uses Brute Force for both primary and secondary GI engine, unless Light Cache is used from file.
Light Cache can be used as secondary GI engine with V-Ray GPU for production rendering. Brute Force is always used as the primary GI engine. In Interactive mode, however, Brute Force is always used for primary and secondary GI engine, regardless of the GI engine settings, unless you load your Light Cache from a file. The reason for that is that the Light Cache is view dependent, and recalculating it every time the camera changes its position in Interactive mode decreases performance.
Procedural textures are supported for GPU bump maps, but because V-Ray GPU is a very different engine, the bump map itself can look a bit different compared to V-Ray.
If you get the following error message, this means that some or all of your video cards do not have sufficient memory to load the scene.
To solve this problem, you can enable texture resizing for GPU rendering and set a texture size limit. This will cause V-Ray GPU to use smaller textures for rendering to conserve memory. See more information on GPU texture resizing.
The difference in render speeds depends on the video cards and the CPUs that are compared, as well as on the scenes used as benchmarks. It is normal to achieve a big speed boost with the GPUs compared to the CPU with some scenes and to have equal performance with others.
Yes, you can speed up your rendering using Distributed Rendering (DR) on multiple systems with CUDA enabled devices. This can be easily set up using V-Ray Swarm.
Keep in mind that some drivers may have limitations and may not be able to use GPUs if there is no monitor attached to the machine or you are logged in via Remote Desktop (for example). Check the GPU vendor documentation for more information.
There are two ways to start interactive rendering with V-Ray:
V-Ray GPU is not officially supported on macOS.
It works only with C++/CPU devices. V-Ray GPU can still be used in distributed rendering where a macOS machine runs the CUDA engine on a CPU device together with Windows/Linux machine(s) running CUDA engine on GPU device(s).