With Core i7 comes new architecture and a new memory controller. No longer is the memory latency stifled by the use of a middleman (North bridge), the memory controller is now on die which has also allowed an expansion from Dual to Triple channel. Of course DDR3 does not need to be run in triple channel, much the same as DDR2 didn't need to run in dual channel but for optimum performance it is highly recommended that you run DDR3 in triple channel mode.



Link: Overclock3D