Multiple Graphics Cards

Copied from the old Lightact Answerhub.


What is the behavior with multiple graphics cards in the same machine? Is the GPU for Lightact rendering selectable?

Thank you again.

Hi Jason,

I wouldn’t know. We haven’t done any tests yet although we talked about it some time ago. Inside Lightact there is, at the moment, no select GPU feature.

If you perform any tests, feel free to let us know your findings.


By curiosity and as I’m new to this forum and product, does anyone has successfully used Lightact with multiple GPU. Like my unreal runs on one GPU and Lighttact running on another? Any advancement or roadmad in that direction. The reason why I ask is sometime I need all the power I can from one GPU, or I might have a very large Mosaic display (using nVidia Quadro) using sync card and 2 to 4 connected GPUS…


Hello Remus,

and welcome to our Answerhub!

We haven’t done any tests on multi GPU systems yet and although I believe some of our users have, I don’t know what were their results and if it worked at all.

However, as far as I know, the performance might not be as much better as you might hope. The reason might be that the shared texture would probably need to be copied between both GPUs and as they are usually quite large this would take some time.

Our development efforts are focused on multi server solutions that would work well with Unreal’s nDisplay. I’m happy to say that it’s going quite well, so in Lightact v3.2.2 you’ll be able to have several machines working in-sync on the same Lightact and Unreal projects.

I hope this helps!

Best regards,

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A bit late, but we’ve done some tests with this. Using NVidia Control Panel it is possible to choose on which GPU LightAct will run.

More information about it here: