Render to an Nvidia Quadro SDI with key

ok, but i’m kind of confused. I’m judging here if we can jump in UE to do some broadcast works.
But we need a key and, as far as i know these nvidia cards http://www.nvidia.com/object/product_quadro_sdi_output_us.html can output the ARGB directly from the GPU so do UE output the full ARGB ?