Bit-Tech published an in-depth look at Nvdia's Hybrid SLI technology

On the whole then, I'm quite excited by the prospects of Hybrid SLI but I can't help but feel that there are some things that Nvidia could have improved in hardware---and I'm not even considering software at this point because it's early days---to make the technology that bit more appealing. The real kicker for me is the display support on the nForce 700a series motherboards because, from everything I've seen so far, there is only one digital output available.

That's not good for anyone who runs dual digital displays---like me for example---because you either leave your power hungry graphics card turned on with the displays plugged into the digital ports on it, rather destroying the point of having HybridPower technology in the first place. Alternatively, you could run one of the displays on the analogue VGA port on the motherboard and the picture quality is awful. With dual digital outputs, you can at least use one or two DVI-to-VGA converter(s) to connect your CRT monitors up to the motherboard -- and the best part of it is that the picture looks just as good when you use a DVI-to-VGA converter.

I have asked Nvidia why it made this design decision, but my questions on the subject are yet to be answered -- I've been promised an answer though, so I will update this when one arrives. Hopefully, I'm wrong and the chipset does actually support dual digital displays but given how long it's taken to get an answer, I am not too confident in that being the case.

Aside from this point though, Hybrid SLI looks to be an incredibly sound technology on paper, but we're going to have to reserve final judgement until we actually have hardware (and drivers) to test this properly.

Nvidia's Hybrid SLI technology