How to Use Two Identical Capture Cards in OBS

Using two identical capture cards in OBS Studio often leads to hardware conflicts, resulting in only one card displaying video at a time. This article provides a step-by-step guide to resolving this common issue, covering USB bandwidth distribution, device initialization workarounds, and software-based passthroughs to ensure both devices run smoothly and simultaneously.

1. Resolve USB Host Controller Bottlenecks

The most common reason two identical capture cards cannot run simultaneously is USB bandwidth exhaustion. Most motherboards route multiple external USB ports through a single USB host controller. When two high-bandwidth devices (like 1080p or 4K capture cards) try to use the same controller, one will fail to initialize.

• Spread the Load: Plug one capture card into the back of your computer (directly into the motherboard I/O) and the other into the front panel. Front and back ports often run on different internal controllers.
• Avoid USB Hubs: Connect both cards directly to the motherboard ports rather than a USB hub, even if the hub is externally powered.
• Install a PCIe USB Expansion Card: If your motherboard lacks separate controllers, installing a PCIe USB expansion card will provide a completely dedicated hardware path and independent bandwidth for the second capture card.

2. Differentiate the Devices in OBS

When OBS detects two identical devices with the exact same name (such as “USB Video”), it may fail to distinguish between them, causing one source to remain black.

• Open OBS Studio.
• Add the first capture card as a Video Capture Device and set its resolution, FPS, and video format manually (do not leave them on “Device Default”).
• Add the second capture card as a separate Video Capture Device.
• Manually configure the second card’s settings to be slightly different (for example, change the Video Format from YUY2 to MJPEG, or change the resolution). This forces OBS and Windows to treat them as distinct streams.

3. Use Manufacturer Software as a Passthrough

If OBS still fails to capture both devices directly due to driver limitations, you can bypass OBS’s direct device capture by using companion software.

• Open the manufacturer’s proprietary software (such as Elgato Camera Hub, RECentral, or a generic media player like VLC) and set it to display the feed of the second capture card.
• In OBS, instead of adding a Video Capture Device, add a Window Capture or Game Capture source.
• Target the companion software window to bring the second camera feed into your OBS scene.

4. Force a Driver Reinstallation

For budget or generic HDMI-to-USB capture cards that use the default Windows UVC (Universal Video Class) driver, Windows might assign the exact same hardware ID to both cards, causing a registry conflict.

• Open Device Manager and expand Cameras or Sound, video and game controllers.
• Right-click one of the duplicate capture cards and select Update driver.
• Choose Browse my computer for drivers > Let me pick from a list of available drivers on my computer.
• Select an alternative compatible driver (such as “USB Video Device” instead of a brand-specific driver, or vice-versa) to force Windows to assign a unique driver instance to that specific USB port.