Troubleshooting LightSync

This guide provides a structured approach to troubleshooting sync issues between multiple servers in a LightSync session.

Common symptoms

• Outputs are visibly out of sync

• Texture motion is not smooth

• Performance graphs contain large periodic spikes

• Synchronization is unstable or inconsistent

Before You Start

LightSync synchronizes all participating servers. If one server is unable to maintain stable frame timing, synchronization issues may occur across the entire system.

Before troubleshooting LightSync, verify that each server is operating correctly and reduce the setup to the simplest possible configuration.

Before you read further, please verify the steps in this guide for each server in the cluster.

Simplify the setup

Hardware configuration

• One GUI display (per server)

• One Output display (per server)

• Synchronize output display using either Genlock or Framelock

  • GUI display should not be synced

  • If Primary doesn't have an output display, Framelocking or Genlocking is not required

• All displays use the same refresh rate

• The project framerate matches the display refresh rate

• Direct connection (if possible)

Network configuration

• Dedicated switch and network

• Only LightAct machines are connected

• No unnecessary network traffic

Close unnecessary applications

• Remote Desktop sessions such as VNC Viewer, TeamViewer, AnyDesk,...

• Web browsers

• GPU monitoring tools

• NVIDIA Control Panel

• Other unnecessary applications running in the background.

Good to know: Applications that interact with desktop rendering can affect synchronization.

Verify Stable Synchronization

A single server occasionally missing a frame can affect synchronization across the entire system.

1. Establish cluster

2. In Output Maps window Enable output displays and set Content override to Strobe

3. Begin LightSync session

4. Observe common symptoms

Healthy behavior

• Graphs are generally stable

• Small fluctuations are acceptable

• Outputs appear visually synchronized

Problematic behavior

• Large spikes appear regularly

• One machine behaves significantly differently from the others

• Outputs visibly drift or stutter

If synchronization is stable in the simplified setup, gradually reconnect the remaining equipment until the issue reappears.

Good to know: If you're using multiple output displays, configure them as a single NVIDIA Mosaic display.

Collect diagnostics

If synchronization issues persist, collect and send the following information to [e-mail].

Output Recording

• In Output Maps, enable the diagnostic Render overlay and record a video of all output displays.

• The information of the Render overlay should be visible on the recorded video.

This feature is available for LightAct version 4.16.0 or newer.

NVIDIA Information

• Provide a screenshot of NVIDIA Control Panel → View System Topology

• This contains important information about

  • GPU model

  • Driver version

  • Synchronization configuration

Package for support

• Please follow these instructions