Using multiple GPUs

Hi,

For our project, we need to render to multiple projectors at high frame rate. This will not be possible with only one graphics card. Even the Titan X will not be powerful enough. So we are trying to figure out what we can do to make multiple GPUs work.
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I understand from this forum that SLI is not supported by UE. One of the reasons is that most multiple GPU solutions use the AFR (Alternate Frame Rendering) method and that is not possible for UE because in UE the information of previous frames is needed during the rendering process. Because we need low latency the AFR method is not suitable for us anyway. We are more thinking about the SFR (Split Frame Rendering) method.
Now there are rumours that DX12 supports this. Does this mean we can use multiple GPUs as soon as DX12 is supported by UE?

If not, will it be possible (and doable) to add this ourselves once DX12 is supported by the engine?

Is it correct that there is already a prerelease of UE that uses DX12? If so, does this support the SFR or any other feature suitable for multiple GPUs?

Is there anything else we can do to use multiple GPUs?

I would also like Split Frame rendering support in UE4.