I'm sure you've read at least one nForce 780a motherboard review by now. LegitReviews goes a bit deeper into what makes the 780a chipset special: Hybrid SLi. They explain the tech, & include some benchmarks.

"Having the ability to turn off the discrete graphics at will is one of the coolest new features we have seen on a PC. It's amazing that it took this long for someone to figure it out, but the time has finally come."