How to Use Dual GPUs in OBS Studio for NVENC

Using two graphics cards in OBS Studio allows you to distribute the workload of rendering your scene and encoding your video stream. This guide provides a step-by-step walkthrough on how to configure OBS Studio to use your primary GPU for rendering game graphics and scene composition, while offloading the NVENC encoding process to a secondary NVIDIA graphics card.

Understanding the Dual GPU Workflow in OBS

Before configuring the settings, it is important to understand how OBS handles dual GPUs.

• Rendering (GPU 0): OBS Studio always renders the preview and composes the video frames on the primary GPU (the one your main monitor is plugged into, usually GPU 0).
• Encoding (GPU 1): The NVENC encoder can be instructed to compress the rendered frames using the NVENC chip on the secondary GPU (GPU 1).

Note: Transferring rendered frames from the primary GPU to the secondary GPU requires moving data across the PCIe bus. This can sometimes introduce system latency or performance drops. However, if your primary GPU is heavily bottlenecked, offloading the encoder can help stabilize frame rates.

Step-by-Step Configuration

To configure OBS Studio to use your secondary GPU for NVENC encoding, follow these steps:

1. Open OBS Studio.
2. Click on Settings in the bottom-right corner, or go to File > Settings in the top menu.
3. In the Settings window, click on the Output tab in the left sidebar.
4. Change the Output Mode dropdown at the top from Simple to Advanced.
5. Navigate to either the Streaming or Recording tab, depending on which output you want to configure.
6. Set the Video Encoder to NVIDIA NVENC H.264 or NVIDIA NVENC HEVC/AV1 (depending on your card’s capabilities).
7. Scroll down to the encoder settings section.
8. Locate the field labeled GPU. By default, this is set to 0 (your primary graphics card).
9. Change this value to 1 to target your secondary NVIDIA graphics card.
10. Click Apply, then click OK to save the changes.

How to Identify Your GPU Numbers

To ensure you are targetting the correct card, you can verify your GPU index numbers in Windows:

1. Right-click the Windows Start button and select Task Manager.
2. Click on the Performance tab on the left.
3. Look at the bottom of the list to find your GPUs listed as GPU 0 and GPU 1.
4. Confirm that the card you want to use for encoding is labeled as GPU 1. If you have three cards, you can use the corresponding index number (e.g., 2) in the OBS settings.