I do understand how multi-adapter compatibility functions in OBS, perhaps my wording was not the best (Been under the weather for a week) and more detail could have been added...
I wonder if in nVidia settings the use of SFR or AFR makes any difference to the outcome?
I wonder if it would be feasible for any dev of OBS to look into implementing a delay of the frame grab from the GPU (preferably master GPU in SLI/X-Fire configurations) selected when there is a SLI/X-Fire configuration detected in the system. One would have to ensure a dynamic allowance for the rendering time for multiple cards though, which would vary greatly dependent upon architecture of the multi-GPU installation.
In either case, the coding in OBS would need to allow for the delay caused by the workload of the 2nd GPU then the subsequent workload of the first GPU rendering the entire image before pushing it for display.
Even in my layman's knowledge of code I can understand why the route was taken to grab the frame from RAM if SLI/X-Fire was being used as an alternative to introducing a delay of sorts to allow for the 2nd/3rd/4th GPU then the workload of the master GPU to finish their rendering tasks before grabbing the entire frame output.
The CPU ability to process the frame to push the frame to each GPU would come into play as well...
The main issue I can actually see is not so much the delay to allow for the workload of the multi-GPU setup, it is more the introduced delay by the CPU as it has to process the frame X number of times more than once... As CPU load increases, especially if one was to be using x264 software encoding for recording/streaming it could induce a negative impact to the point where performance would be worse than if it were a single card configuration.
