"The license key is an important feature since it is dependent on certification by NVIDIA, which includes verification of stability, power, compatibility, and layout. If a motherboard is certified, then NVIDIA's drivers will enable SLI functionality.
Some certified motherboards with native slot configurations will support 2-way and 3-way SLI configurations. In this case, native slot configurations consist of PCI-Express slots that are connected to Intel's X58 chipset. However, X58-based motherboards with NVIDIA's nForce 200 chip will be able to provide full-bandwidth x16 connections for 3-way SLI. These systems will also be able to support four x16 PCI-Express slots, creating maximum bandwidth for 3-way SLI systems with a dedicated PhysX GPU."