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the central platform of the motherboard – Le Crab Info

The chipset is a set of components that manages communications between the processor and the components connected to the motherboard of the computer (RAM, graphics card, hard drive, etc.) as well as external peripherals. In other words, the chipset acts as a bridge between the processor and other components. It’s here motherboard central platform ! As you will see, the chipset plays a crucial role in the performance of your system 🙂

The chipsets are generally designed to work with a specific family of processors. In fact, a new generation of processor almost always comes with a new generation of chipset. Chipsets must indeed keep pace with the evolution of components (processor, RAM, etc.) which use ever more efficient technologies. For example, in 2017, the AMD B350 chipset arrived at the same time as the AMD Zen processors; in 2013, the Intel Z87 chipset arrived at the same time as the Intel Haswell processors.

What differences can be found between two chipsets from the same family?

For example, for Intel 6 series family chipsets launched at the same time as the Intel Sandy Bridge processors, there are models that incorporate a graphics processor but which do not allow the processor to be overclocked (Intel H67), others without a graphics processor but which allow overclocking (Intel P67) or models that have additional functions such as SSD Caching or USB 3.0 (Intel Z68).

For a long time, the chipset was based on the architecture Northbridge/Southbridge, two chips installed on the motherboard.

A two-chip Northbridge and Southbridge chipset – Source: karbosguide.com

Northbridge / Southbridge Architecture

The chip Northbridge manages communications between the processor and fast peripherals such as the RAM (via the memory bus), the Graphic card (via the PCI Express graphics bus) and the Southbridge (via an internal bus). The Northbridge is directly connected to the processor via the front-side bus (FSB).

The Northbridge was generally associated with a Southbridge. The Southbridge managed communications with input / output devices (IDE, SATA, USB, Ethernet, etc.). Apart from the monitor, all the peripherals that you plugged into your PC passed through this chip.

Source: bbc.co.uk

For the sake of completeness, here are all the functions of the Northbridge and those of the Southbridge:

  • Northbridge : system bus (FSB), memory bus, graphics bus (AGP or PCI Express), clock buffer, clock generator and Southbridge.
  • Southbridge : PCI bus, ISA, SATA, IDE, USB, PS / 2, audio, network and clock generator.

Intel Hub Architecture (IHA)

In 1999 and starting with the Intel 810 chipset, the Northbridge and Southbridge were respectively replaced by the Memory Controller Hub (MCH) – or the Graphics and Memory Controller Hub (GMCH) when this included a graphics processor – and the I / O Controller Hub (ICH). These two controllers are connected by an internal bus and form theIntel Hub Architecture (IHA).

MCH is similar to Northbridge and allows to control the graphics card in AGP and the RAM; the ICH is similar to the Southbridge and allows control of input / output devices.

Intel Hub Architecture (IHA) – Source: Ars Technica

Thanks to a 266MB / s high-speed bus that connects the ICH to the MCH, the Intel Hub Architecture (IHA) is much faster than the old Northbridge / Southbridge architecture, which connected its two chips via a PCI bus with a bandwidth of 133 MB / s. Much later, in 2008, the ICH version 10 will implement a new bidirectional interface – DMI (Direct Media Interface) – of 10 Gb / s, accelerating the exchanges between the MCH and the ICH.

Platform Controller Hub (PCH)

Over the years, this system architecture has ended up show your limits. Indeed, the speed of the processors continued to increase while the bandwidth of the FSB did not progress, thus causing a bottleneck. To put it simply, it was as if we were in a work chain with a worker (the processor) and a conveyor (the FSB): the worker performs his tasks very quickly but the conveyor is so slow that it takes time to send him new ones. During this time, the processor poirote and the chain of work (the system) turns to the slows down.

Old architecture with MCH and FSB (Intel series 4 chipsets) – Source: Dr Dobb’s

To remedy the problem and improve the performance of the system, the FSB has therefore been replaced by theHyperTransport at AMD and by the QuickPath Interconnect (QPI) at Intel. Thus, the worker (the processor) no longer works with the old conveyor (the FSB), but with a brand new ultra-fast (the QPI or the HyperTransport) which gives him the new tasks to accomplish much faster! The first implementations of QPI with Intel Nehalem processors will offer a bandwidth of 25.6 Gb / s, i.e. double what an FSB offers classic with an Intel Core 2 Extreme processor (12.8 GB / s).

But processor manufacturers don’t stop there: they decide to withdraw the memory controller of the Northbridge and integrate it directly in the processor. This change has borne fruit as it has allowed reduce latency between processor and RAM. In this new architecture, the MCH gives way to I / O hub (IOH) with Intel “Tylersburg” series 5 chipsets (Intel X58).

New architecture with IOH and QPI bus (Intel “Tylersburg” series 5 chipsets) – Source: Dr Dobb’s

And it’s not over ! In parallel, the PCI Express graphics controller, which manages the communication between the CPU and the graphics card, is also moved to the processor with the Intel 5 series “Ibex Peak” chipsets.

These implementations signed the death of the traditional Northbridge which will disappear. A new system architecture – which is still in place today – is emerging: as the main functions of the Northbridge are integrated into the processor, all the functions of the Southbridge and a few remaining of the Northbridge (e.g. clock buffer) are consolidated in a single new chip: the Platform Controller Hub (PCH), connected to the CPU via the Direct Media Interface (DMI).

On the left, the old architecture (Intel series 4 chipsets); on the right, the new one (Intel series 5 “Ibex Peak” chipsets) – Source: National Instruments

The main functions of the old Northbridge are now integrated in the processor : in addition to the CPU cores, there is the memory controller and the PCI Express graphics controller.

Die of an Intel Lynnfield processor, there is a memory controller and a PCI Express graphics controller

Thus, the chipset evolves from an IHA architecture to two chips (GMCH and ICH) to a PCH architecture with a chip. This new architecture reduces the size of the motherboard and makes small devices happy.

The Intel X99 PCH Chipset (Intel 9 Series Chipset) Single Chip with its heat sink – Source: ocdrift.com
The Intel X99 PCH Chipset (Intel 9 Series Chipset) Single Chip without its heat sink – Source: ocdrift.com

How it works ?

The following diagram will allow you to see more clearly:

On the right, the new system architecture with Intel 5 series chipsets – Source: DailyTech

the processor (Processor) integrates a memory controller (IMC) to communicate with the RAM (DDR 3) and a graphics controller (iGFX) to communicate with the Graphic card in PCI Express (PCIe Graphics). The processor is connected to the PCH (Intel 5 Series Chipset) – which communicates with I / O devices – via an interface specific to Intel, named DMI (Direct Media Interface). Only the graphics controller (iGFX) – integrated in the processor – uses a specific interface, named FDI (Flexible Display Interface), so that the images generated by the Graphic card (PCIe Graphics) are sent to the PCH which will send them to the monitor (Display).

Still alive ? 😛

In 2010, using Westmere generation Intel processors, a new step was taken: the graphics processor, which could be found as an option in the PCH, is moved to the processor package. The chipset, in its PCH form, once again loses an important function, after the memory controller and the PCI Express graphics controller.

Intel Westmere processor (right) integrating a central processor, graphics processor and memory controller on two chips and in the same package

You see, over the years, the role of chipset has changed a lot. And even though he lost a few feathers, there is still a essential component of your system: it is again it that manages the USB, SATA, PCI Express, LAN and HD Audio ports! For the moment … 😉

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