Modern Motherboards: Out with the old and in with the “new” new

The Socket

Each motherboard supports a specific processor type. AMD and Intel each have proprietary standards and chip technologies which determine the type of socket required. As the physical architecture of the processors shrink, the future is heading toward multi-core processors. Intel and AMD both released “dual-core / core-duo” chips which contain two processors in the same package and even smaller which formerly contained a single processor. Quad core and even 8 core processors soon followed with exciting performance gains ahead as the technology continues to evolve.

The Northbridge

In the standard ATX type motherboard, the “Northbridge” is a core logic chip located towards the top of the board. The Northbridge connects the CPU to the motherboard via a high speed bus. Northbridge chips are also known as “Memory Controller Hubs” and serve to handle communications between the Processor, the system RAM and the Expansion Bus. As you might guess, the Northbridge is specific to certain processor types and also controls what type of RAM can be used as well as the capabilities of the PCI, AGP or PCIe systems. Newer processors such as the AMD64 move certain functions such as the memory controller section of the Northbridge onto the processor.

The Northbridge also affects the Processor speed as it sets the benchmark for the CPU’s clock. The last couple of generations of motherboards have added cooling, either a passive heat sink or a small fan as higher motherboard data speeds translate to higher heat loads in the Northbridge. The remaining function of the Northbridge is to route communication to a second core logic chip known as a “Southbridge”.

The Southbridge

The Southbridge is usually located below the Northbridge via a lower speed bus. The traditional link was made using the PCI bus but given the performance bottleneck as Processors and Motherboard speeds accelerated the standard has moved on to higher speed links. The Southbridge is also known as the “In / Out Controller Hub or ICH”.

It connects lower speed devices to the system such as USB ports, the old PCI standard bus, (newer motherboards still often include PCI as well as PCIe for backwards compatibility), storage controllers, (IDE, SATA, PATA and on-board RAID) and on-board peripherals such as sound and Ethernet. More critical to the system, the Southbridge handles DMA, (direct access to system memory without communicating via the Processor) and system Interrupts, (a system for attached devices to communicate with the Processor). The Southbridge sometimes also handles input device communications for the mouse and keyboard otherwise this is handled by a component known as the “Super I/O”. The Southbridge connects to the next core hardware controller on the motherboard, the “BIOS”.

The BIOS

Usually located just below the Southbridge is a small but critical chip known as the “BIOS”, short for “Basic Input / Output System”. The BIOS is also known as “firmware” or “an operating system for the hardware” and controls communication between the system hardware on startup and the system software, (the Operating System). BIOS chips have evolved from ROM, (read only memory) to EPROM to Flash type Memory. This allows vendors to supply upgrades to the motherboard’s hardware capabilities via “flash” upgrades. The growing trend is dual or even quad flash RAM BIOS chips with a backup copy of the BIOS stored in case of corruption from a virus or a bad flash upgrade. BIOS originated back in the days of DOS when the BIOS was capable of handling a number of the functions now controlled by the North and South Bridges.

The primary purpose of the BIOS now is to “boot” the computer, a process where the computer’s hardware is tested, brought online and handed off to the operating system. Expansions to the BIOS, namely the ACPI standard have added functions such as thermal management, (variable speed fans and heat alarms), hot swapping of hardware and power management. Future trends in BIOS include “EFI” a newer standard encompassing the ACPI functions with promises of further functionality in the coming iterations. EFI is supported by some Linux systems as well as the 64 bit version of Windows Vista. Google is currently sponsoring the development of an open-source BIOS standard in response to commercial BIOS being controlled via licensing agreements between PC vendors and a few companies which hold the original patents.
Keeping up to date through your motherboard

As you can see, the future of PC technology can be somewhat predicted by knowing the various parts of the motherboard and taking time to research the ongoing development in each area. By combining the knowledge that motherboards a year from now will most likely support quad core processors, PCIe v2 and EFI you can make an educated guess as to when might be the best time to consider upgrading your system. (Do you really want to jump into the first quad core capable desktop system knowing graphics cards and other PCIe devices will be twice as fast a few months later?)

PCIe v2 has been released and its appearance in consumer hardware should be a matter of months at this point. The other thing to keep in mind is the fact that there will always be something faster, bigger and better coming out just soon enough after you’ve invested in upgrades. Unless you’re a gadget fanatic / early adopter who absolutely has to have the latest and greatest your timing should be a balance between desired progress and economy.

Resources:

PCI Standard: http://www.pcisig.com/home/
Graphics and Core Logic – Nvidia: http://www.nvidia.com/page/technologies.html