Fix Two Capture Cards Not Working in OBS Studio

Using multiple capture cards in OBS Studio is an excellent way to stream multiple camera feeds or consoles simultaneously, but hardware conflicts often prevent both devices from being recognized at the same time. This article explains the two primary causes of this issue—USB bandwidth limitations and identical hardware IDs—and provides clear, actionable steps to resolve the conflict and get both capture cards working together.

1. Resolve USB Bandwidth Overload

The most common reason OBS Studio fails to read two capture cards simultaneously is USB controller saturation. Capture cards transmit massive amounts of uncompressed video data. If both cards are plugged into USB ports that share the same internal USB controller (or Root Hub), the controller will run out of bandwidth, causing one or both cards to freeze or disconnect.

To fix USB bandwidth issues: * Separate the Ports: Do not plug both capture cards into adjacent USB ports. Plug one card into the back of your motherboard and the other into the front panel ports, as these usually run on different internal controllers. * Avoid USB Hubs: Connect both capture cards directly to your computer. Unpowered USB hubs cannot handle the data and power requirements of multiple capture devices. * Use Different USB Standards: If possible, plug one card into a USB 3.0 (blue) port and the other into a USB 2.0 (black) port, provided the second card supports USB 2.0 speeds at a lower resolution. * Install a PCIe USB Expansion Card: For desktop users, installing a dedicated PCIe USB expansion card is the most reliable way to add a completely separate USB controller to your system.

2. Differentiate Identical Capture Cards (Hardware IDs)

If you are using two identical capture cards (such as two of the same generic HDMI-to-USB dongles), Windows and OBS Studio may struggle to distinguish between them because they share the same hardware ID and driver name.

To resolve identical device conflicts: * Change the Input Properties in OBS: Double-click on the first capture card source in OBS. Change the Resolution/FPS Type from “Default” to “Custom.” Set a specific resolution (e.g., 1920x1080) and frame rate. Do the same for the second card, but set it to a slightly different resolution or frame rate (e.g., 1280x720) to force Windows to register them as separate feeds. * Update to Unique Drivers: Check the manufacturer’s website to see if they offer a proprietary driver or configuration utility. Proprietary drivers can sometimes assign unique identifiers (e.g., Cam Link 1 and Cam Link 2) to identical hardware. * Use Different Brands: If software workarounds fail, the most foolproof solution is to ensure your two capture cards are different brands or models (e.g., one Elgato card and one EVGA card). This guarantees they will use different drivers and will never conflict.

3. Adjust OBS Source Settings

Sometimes the conflict is purely within OBS Studio’s scene configuration. Ensure you are setting up the cards correctly within the software: * Create Separate Sources: Do not use the “Add Existing” option when adding the second capture card to a scene. Always select “Create New” and choose the specific device from the dropdown menu. * Deactivate When Not Showing: Open the properties of each capture card source in OBS and check the box that says “Deactivate when not showing.” This releases the hardware resource when you switch scenes, reducing the overall load on your USB controllers.