So... here I am:
Working fine on my System.
nVidia has SLI Option = "SLI Rendering mode" in the driver control panel.
Set to AUTO = only one GPU renders the Scene in BlackInk
Set to Alternate Frame Rendering 1 (AFR1) = Both GPUs share the work 50/50
That IS how we want it to be!
Set to Alternate Frame Rendering 2 (AFR2) = Both GPUs share the work unevenly varies
between 70/30 or 60/40 (has to do with AFR2 because here, not the Frames are distributed over the two GPUs,
but the upper half of the Screen is rendered by GPU1 - the bottom half by GPU2)
So here AFR1 shoud work FINE and BETTER!