For 4K capture at 60fps you need the USB Capture HDMI 4K Pro or the USB Capture HDMI 4K Plus via USB, or one of the Pro Capture 4K Plus PCIe cards for a permanent workstation. Make sure your USB port is genuinely USB 3.0 — marked in blue or with the SS (SuperSpeed) symbol.
Magewell USB Capture devices are driver-free on all major operating systems. Plug in the device and your HDMI source, then open OBS and add a Video Capture Device source. The Magewell device should appear in the device dropdown immediately. If it does not, try a different USB 3.0 port or restart OBS.
In the Video Capture Device properties, set Resolution to Custom and enter 3840x2160. Set FPS to 60. Set Video Format to NV12 or I420. Leave everything else at default.
Go to Settings → Video and set Base Canvas Resolution to 3840x2160. Set Output (Scaled) Resolution to 1920x1080 for streaming or 3840x2160 for local recording. Set FPS to 60.
In Settings → Output, switch to Advanced mode. Select your GPU encoder: NVENC (NVIDIA), AMF (AMD), or QuickSync (Intel). These hardware encoders handle 4K60 without the CPU load that x264 would require at this resolution.
OBS defaults to Rec. 709 which matches most HDMI sources. If you see washed-out colours, go to Settings → Advanced and ensure Colour Format is set to NV12 and Colour Space to 709.
Dropped frames: Usually a USB bandwidth issue. Make sure no other USB 3.0 devices share the same USB controller. Check Device Manager under Universal Serial Bus Controllers.
Black screen: HDCP-protected sources cannot be captured. Camera outputs, switcher outputs, and gaming consoles in standard output mode are fine.
High CPU usage: Switch to a GPU encoder in OBS. If already on GPU encoding and still seeing high load, reduce the bitrate or switch to a lower preset.