Configure Dual GPUs for NVENC Encoding in OBS Studio

Using a secondary NVIDIA graphics card dedicated solely to encoding in OBS Studio can help offload processing tasks from your primary gaming GPU. This guide provides a straightforward, step-by-step walkthrough on how to configure OBS Studio to target a second graphics card for NVENC encoding, along with critical performance considerations you should keep in mind before setting up a multi-GPU configuration.

Step 1: Identify Your GPU Index Numbers

Windows assigns index numbers to your graphics cards starting from zero. Before configuring OBS, you need to know which number corresponds to your secondary card. 1. Right-click the Windows Start button and select Task Manager. 2. Click on the Performance tab. 3. Look at the left sidebar to locate your GPUs (labeled as GPU 0 and GPU 1). 4. Note which GPU is your primary gaming card (usually GPU 0) and which is your secondary card (usually GPU 1).

Step 2: Configure OBS Studio to Use the Secondary GPU

Once you know the index number of your secondary GPU, you can assign the NVENC encoder to it inside OBS Studio. 1. Launch OBS Studio. 2. Click on Settings in the bottom-right corner (or go to File > Settings). 3. Select the Output tab from the left menu. 4. Change the Output Mode dropdown at the top from Simple to Advanced. 5. Click on 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 HEVC/AV1 if supported by your secondary card). 7. Scroll down to the bottom of the encoder settings box to find the setting labeled GPU. 8. Change the value from 0 (the default primary GPU) to 1 (or the corresponding index of your secondary GPU). 9. Click Apply and then OK to save your changes.

Important Performance Considerations

While routing encoding to a second GPU sounds like an easy performance boost, it can sometimes result in worse system performance due to how OBS captures video.

• PCIe Bandwidth Limitations: OBS renders your stream canvas on your primary GPU (where the game is running). If you select GPU 1 for encoding, the rendered frames must be copied from GPU 0 to GPU 1 across your motherboard’s PCIe lanes. This transfer can introduce bus bottlenecks, causing dropped frames or micro-stutters.
• Modern NVENC Efficiency: NVIDIA’s NVENC is a physically separate microchip on the graphics card. Using it on your primary GPU does not impact your game’s 3D rendering performance. For most modern setups, leaving OBS on GPU 0 is highly recommended for optimal efficiency.