JAY said:
what is this north and south bridge on motherboards??
On traditional chipset configurations (nForce 3/4 and a few SiS chipsets are an exception), there are two major chips on the motherboard. The northbridge (which is usually what's referred to in a chipset pair, like the i945/955X for example) houses the graphics controller with AGP/PCIe and the memory controller. In the past, the northbridge and Southbridge (like ICH5R) were linked by the PCI bus, but Intel started a trend with the 8xx series chipsets by creating a private bus between the two. This is what's referred to as a 'hub architecture'.
The southbridge typically contains the storage controller (IDE, SATA, Floppy), USB, legacy ports (PS/2, Serial/COM, Parallel), LAN, and the PCI bus controllers.
The nForce 3/4 (except the Intel nF4 SLI which is like the traditional configurations) is basically a southbridge with the AGP/PCIe controllers added in. The Athlon 64 design (includes Athlon FX, S754 Semprons, Opterons) integrates the memory controller into the CPU to improve performance (the biggest reason for the speed increases if my facts are straight). As a major part of the northbridge is gone, it can be more efficient to just do away with the memory controller on the northbridge. So far, VIA has ignored this and might be part of the reason they've faded from the picture (along with the nF3/4's marketing, better feature set, and being very overclocking friendly). VIA is still using the traditional northbridge/southbridge configuration. Even ULi (formerly ALi) is moving toward single chip solutions.
That's all for today's geek history lesson. ;)