QuickPath Interconnect is the name of the external bus used by the Intel forthcoming CPUs with integrated memory controller, like the Core i7. In this tutorial we will explain how this bus works.
"Since the beginning of times Intel CPUs use an external bus called Front Side Bus or simply FSB that is shared between memory and I/O requests. The next generation of Intel CPUs will have an embedded memory controller and thus will provide two external busses: a memory bus for connecting the CPU to the memory and an I/O bus to connect the CPU to the external world. This bus is a new bus called QuickPath Interconnect (QPI) and in this tutorial we will be explaining how it works."