The eternal Quadro vs. gforce question (sync issues and performance)

For an upcoming installation I’m having trouble to decide on the right configuration…
The installation would be 18 1920x1200 projectors all should be synced and they all will display a render of 3D environment.
My first intuition was going with 2 machines each with an RTX 3090 and 5 Datapath fx4 (2 on connected on the first machine and 3 on the second). Then I would Genlock the datapaths.
The other route is to go the quadro much more expensive route. does the quadro sync matter anything if the fx4s are already genlocked?

It is proven that the gforce cards are faster for realtime rendering so if i go with quadro cards i pay more for less performance.

Another Idea is to put the 2 GPUs on the same system and use GPU affinity.

It depends what level of sync you are trying to get. The only thing genlocking the x4s will ensure their refresh intervals are at the same frequency. Useful if you are filming the screens, to sync them with the shutter frequency of studio cameras. If the content they are showing is already in sync, then that genlock sync will fix up to a 1 frame offset, incase one was refreshing 0.9999% of a frame earlier than the previous one.
However it doesn’t help you get to the point where your content is synced. The only way to do that is with the Quadro Sync cards (Hardware frame lock on the Window COMP) and Sync In/Out CHOPs.
In reality though, lots of content and venues doesn’t need perfect content sync though. Slow moving or very busy content often won’t show sync issues.

Echoing @malcolm here - for projection a high degree of sync usually isn’t required. At Obscura we ran just about all of our projection shows on multiple machines and used a software sync style approach with great success.

As soon as your content is on video walls - sync matters a LOT. You’ll see a much higher degree of tearing on LED and LCD screens that are split across machines, and across video outputs. The other place sync matters is film - if you’re plan is recording to video, you’ll for sure need sync to line up the shutter / capture and your display refresh.

The other piece to consider about quadro cards over the gtx line is support - typically on the consumer cards you don’t get tier 1 support from NVIDIA. If you’re goin to hand this installation off to a venue or client, it’s worth considering what hardware support might look like. If you have an SLA for the project, then sometimes the extra layer of direct / immediate support is worth going quadro.