With this new chipset you’ll see the C73 northbridge and the MCP55 southbridge chipset. As far as what that means, it means the motherboard will be able to support up to a 1600MHz front side bus.
It will also support 3-way SLI and Hybrid SLI as well as DDR3 memory. They are releasing this DDR3 capable motherboard in the second quarter because everyone is expecting DDR3 prices to drop sometime in the third quarter, it’ll still be expensive, but this chipset is aimed squarely at those willing to spend the extra dough for the higher performance.
There are going to be 2 different sets, the nForce 790i Ultra SLI and the nForce 790i SLI, with the only differences being that the Ultra version will have better over-clocking capabilities and will be able to run the faster DDR3 2000 modules. It is also suspected that the reason for the low number of 780i chipset boards is because compared to the 680i, there isn’t much of a difference, so they are saving their development dollars for the 790i chipset.