The View From Ibex Peak: The P, Q, and H 5 Series Chipsets from Intel

Starting with Lynnfield in the third quarter and Clarkdale as we move into next year, Intel will be bringing Nehalem processors to the mainstream desktop market. Their Core i7 enthusiast-oriented chips, launched last November, are great performers and reasonably priced considering their power and newness. They have failed to gain the popularity Intel was hoping for, though, but this is likely related to general economic issues.

Intel is now preparing Nehalem’s - admittedly reduced in grandeur - introduction to the mainstream. This includes a new platform, called Ibex Peak, which is quite different from not only the preceding Core 2 platforms, but even the X58/Tylersburg platform which runs the Core i7 Nehalems.

Core 2, and previous Intel architectures, used a northbridge that contained a memory controller and a PCI-e graphics controller. It communicates with the CPU using the Front Side Bus, and with the Southbridge (which controls things like hard drives and USB ports) via DMI, or direct media interface. This configuration, used on motherboards with Intel’s LGA 775 socket, is pictured at right.

Core i7 moved the memory controller onto the CPU itself. It communicates with the X58’s graphics controller (now the north bridge’s main job) by Quick Path Interconnect (QPI) at up to 6.4 GB/s. The north and south bridge are still connected by DMI. This configuration, which is pictured below, uses an LGA 1336 socket.

Lynnfield, likely to be called Core i5, and Clarkdale CPUs, will use the Ibex Peak platform. In addition to the memory controller being on the CPU, as in Core i7, the graphics controller also comes on board the processor. In the case of the 32nm Clarkdale, so does integrated graphics functionality.

Since the work that was done by the northbridge is now being done on the CPU, the Ibex Peak platform doesn’t have one. And since the processor doesn’t need to bus graphics data to a bridge, it doesn’t use QPI. The processor communicates directly with the southbridge, using the lower bandwidth (2 GB/s) DMI. We see this at left. We should also note that while both CPU families have integrated DDR 3 memory controllers, the X58’s above is triple channel, while Ibex Peak’s is the traditional dual channel.

In addition to splitting the enthusiast Core i7/X58 platform from the mainstream Ibex Peak platform, Lynnfield and Clarkdale each get their own version of the Ibex Peak platform.

The main theoretical difference between Ibex Peak in Lynnfield and Clarkdale is the absence or presence, respectively, of what Intel calls Flexible Display Interface. Since Clarkdale has graphics integrated on the CPU, it uses FDI to get the display signal to the southbridge, whence it can be sent to an output on the motherboard where you plug in a monitor. Havendale CPUs do not include graphics, and are meant to deal with graphics cards (which have their own display output), so they don’t have FDI.

The main practical difference is a biggie. It looks like Lynnfield will use an LGA 1156 socket, and Clarkdale will use an LGA 1155 socket. Chips using an LGA 1157 will be sold under the Xeon brand as server products. Thus we don’t worry about them here.

In addition to the integrated graphics/no integrated graphics split, which have different sockets but share the Ibex Peak name, is a split between the home, and office chips. The former will be called Kings Creek, and the latter Piketon. The main difference appears to be in remote administration features: stuff that makes a System Administrator’s job easier like being able to update the Service Pack on dozens of computers at a time.

Piketon will continue Intel’s chipset naming conventions, coming to market as Q prefixed, meaning business oriented, chipsets. The second character, a numeral, indicates the series. The 4 series was the last for Core 2; the Tylersburg X58 and Ibex Peak chipsets are collectively the 5 series. For reference, the X instead of Q is for eXtream, and the final 8 indicates, somewhat redundantly, the top of the line.

Next Page: Q55, Q57, and the P, Q, and H 5 Series