Northbridge v/s Southbridge 
Northbridge:
The Northbridge is one of the two chips in the core logic chipset on a PC motherboard, the other being the Southbridge 
Separating the chipset into the Northbridge and Southbridge 
 The Northbridge typically handles communications among the CPU, RAM, BIOS ROM, and PCI Express (or AGP) video cards, and the Southbridge.[1][2] Some north bridges also contain integrated video controllers, also known as a Graphics and Memory Controller Hub (GMCH) in Intel systems. Because different processors and RAM require different signaling, a Northbridge will typically work with only one or two classes of CPUs and generally only one type of RAM.
The Northbridge typically handles communications among the CPU, RAM, BIOS ROM, and PCI Express (or AGP) video cards, and the Southbridge.[1][2] Some north bridges also contain integrated video controllers, also known as a Graphics and Memory Controller Hub (GMCH) in Intel systems. Because different processors and RAM require different signaling, a Northbridge will typically work with only one or two classes of CPUs and generally only one type of RAM.There are a few chipsets that support two types of RAM (generally these are available when there is a shift to a new standard). For example, the Northbridge from the Nvidia nForce2 chipset will only work with Socket A processors combined with DDR SDRAM, the Intel i875 chipset will only work with systems using Pentium 4 processors or Celeron processors that have a clock speed greater than 1.3 GHz and utilize DDR SDRAM, and the Intel i915g chipset only works with the Intel Pentium 4 and the Celeron, but it can use DDR or DDR2 memory.
The Southbridge Southbridge  typically implements the "slower" capabilities of the motherboard in Northbridge / Southbridge Southbridge 
 The
The Difference between Southbridge 
North and south bridge refer to the data channels to the CPU, memory and Hard disk data goes to CPU using the Northbridge. And the mouse, keyboard, CD ROM external data flows to the CPU using the Southbridge 
The Northbridge is the portion of the chipset HUB that connects faster I/O buses (for example, an AGP bus) to the system bus. Northbridge SI also bigger looking then the Southbridge Southbridge 
The Northbridge and the Southbridge Southbridge 
