SLI requires two supported graphics cards (usually the same model) which you don't seem to be planning on. Is there some specific application you will be using that requires SLI?
I don't believe Decklink Studio supports passing three simultaneous streams to the system; for that, you would normally need something like
Decklink Quad, and then get a custom application that can encode three simultaneous streams. Bottom line, it's not very trivial unless I've been living in a cave for the last few years and missed some major developments with BMD cards.
Osprey 460e on the other hand does allow independent input of up to four streams and prep them for streaming.
What software and/or service do you plan to use for streaming?
Alex Gerulaitis
Systems Integrator
DV411 - Los Angeles, CA