Synchronize GPU Outputs

Synchronized outputs ensure that the content being played appears at the same time across all outputs. To achieve this, LightAct servers typically come with a Sync module, providing smooth display synchronization.


As a pre-requirement, you must ensure that all outputs are exactly the same and that they utilize the same refresh rate and resolution.

Good to know: The refresh rate of the Outputs must be equal to or divisible by the Application framerate that you choose in LightAct. The fps of the content you are playing must also be either equal to or divisible by the Application framerate and the Output refresh rate.

The Application frame rate in LightAct can only be as high as the lowest refresh rate of any of the Outputs connected to the server, including your GUI output.

Good to know: It is best if the Primary Display is set to one of the Outputs you would like to synchronize, instead of the GUI Display itself.

Synchronize the Outputs

To achieve Output synchronization, you must complete the following steps:

  1. Synchronize Displays in NVIDIA Control Panel.

  2. Modify Display Configuration.

  3. Create a single Video Output in LightAct, which covers all individual Outputs that you would like to synchronize.

1. Synchronize Displays in NVIDIA Control Panel

Having a Sync module connected to the server reveals a new tab in the NVIDIA Control Panel, dedicated to synchronization of displays.

You can find this panel under the Workstation collapsible, by clicking on Synchronize displays.

To synchronize the displays on a single server, under The timing server is..., select On this system option. Next, select one of the Displays which you intend to use as an Output.

Under the Select displays to lock to the server, select all of the other Displays that are the same as the previously chosen Display, and which you intend to include in the synchronization.

Click on the Apply button at the bottom right corner of the NVIDIA Control Panel to apply the changes.

2. Modify Display Configuration

In LightAct, you can synchronize your outputs by mapping their content onto one single Video Output, which spans across all individual outputs you want to synchronize. To avoid creating large Video Outputs with redundant pixels, it is best to configure our Displays in a 1xn or nx1 topology, n being the number of Displays.

You can configure your displays in the Set up multiple displays tab of the NVIDIA Control Panel, under the Display collapsible.

Example of a bad Display configuration:

Example of a good Display configuration:

Good to know: It is usually best practice to place your GUI Display on the far left, and your Output Displays on the right.

3. Create Video Output

Finally, in LightAct, you must create a Video Output with a resolution that would fit all of your Output Displays, as positioned in your Display configuration.

For example, in our case, we have a 3x1 Output topology, and each output is set to 1920x1080. This results in a single Video Output with a resolution of 5760x1080.

To finalize the process, the large Video Output should be mapped to the topmost and leftmost point of your Output configuration, so that every pixel falls perfectly where it is supposed to.

Once you enable the Video Output, you should be able to see your content playing across the Synchronized Outputs.

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