Some benchmarks of NVIDIA's Hybrid SLI technology were leaked on Asian websites. OC Workbench writes PC Online tested Hybrid SLI on a Windows Vista system with a MCP78S chipset based motherboard and a GeForce 8400 GS graphics card.
In 3Dmark03, MCP78S 2683, 8400GS scored 5800.
For hybrid SLI, it can operate in two modes, Energy Saver mode or performance mode.
In Hybrid SLI Energy Saving mode, it scored 2700.
In Hybrid SLI Performance mode, the score is 5700. This is shocking as it is slower than a discrete 8400GS graphics card performance.
Enabling Hybrid SLI caused a performance drop of more than 100 3DMarks. It looks like NVIDIA still has some driver tweaking to do before these motherboards are available.