Intel Platform Controller Hub

The Platform Controller Hub (PCH), introduced in 2008, is a family of Intel chipsets. It succeeded the Intel Hub Architecture, which used a northbridge and southbridge instead and first appeared in the Intel 5 Series.

Used in conjunction with Intel CPUs, the PCH controls certain data paths and support functions including clocking (the system clock), Flexible Display Interface (FDI) and Direct Media Interface (DMI). However, FDI is only used when the chipset is required to support a processor with integrated graphics. As such, I/O functions are reassigned between this new central hub and the CPU compared to the previous architecture. Some of the northbridge functions and the memory controller and PCI-e lanes were integrated into the CPU while the PCH took over the remaining functions in addition to the traditional roles of the southbridge. With its design addressing the eventual problematic performance bottleneck between the processor and the motherboard the PCH architecture supersedes Intel’s previous Hub Architecture. The fact that the speed of CPUs kept increasing but the bandwidth of the front-side bus (FSB) did not, resulted in a performance bottleneck.

A motherboard would have a two-piece chipset consisting of a northbridge chip and a southbridge chip under the Hub Architecture. Several functions belonging to the traditional northbridge and southbridge chipsets were rearranged as a solution to the bottleneck. The northbridge is now eliminated completely and its functions, the memory controller and PCI Express lanes for expansion cards, are now incorporated into the CPU die or package.

In addition to all of the southbridge’s functions, the PCH then incorporates a few of the remaining northbridge functions (e.g. clocking). The system clock which was previously a connection is now fused in with the PCH. Flexible Display Interface (FDI) and Direct Media Interface (DMI) are the two different connections that exist between the PCH and the CPU. The FDI is only used when the chipset requires supporting a processor with integrated graphics. The Intel Management Engine was also moved to the PCH starting with the Nehalem processors and 5-Series chipsets.