I’m running the following setup for fighting game tournament livestreams:

We have a gaming PC (PC A) connected to two monitors. Both monitors receive the same signal through an HDMI splitter, as well as a capture card.

The capture card is then connected to our streaming PC (PC B).

On PC B, OBS captures the signal from the capture card and simultaneously livestreams and records at 1080p60. The OBS Program output is also sent to an external TV connected directly to PC B via HDMI. The TV is configured as a third extended display in Windows, and I use OBS’s fullscreen Program projector to show the PGM feed to the audience.

The problem is that the local OBS preview / Program projector sometimes does not look like a consistent 60 fps. It occasionally appears noticeably choppier, as if the frame rate has dropped below 60 fps.

I’ve done some testing:

• The livestream itself looks perfectly smooth at 60 fps when viewed from another device.
• Streaming and recording are using the same encoder.
• All monitors and the TV are set to the same 60 Hz refresh rate.
• However, the local OBS preview / Program output on the TV sometimes appears to drop below 60 fps.
• The locally recorded video also sometimes appears less smooth than the livestream.
• CPU/GPU usage is not significant (12400f/RTX5060, 32gb RAM)

So the strange part is that the outgoing livestream looks like a perfect 60 fps, while OBS’s local preview / fullscreen Program projector and sometimes the recording do not.

What would be the best way to troubleshoot this?

Could this be caused by OBS rendering lag, Windows multi-monitor composition, the fullscreen projector, GPU load, capture-card timing, or something else?

Any suggestions on what OBS statistics, logs, or settings I should check would be greatly appreciated.