Intel Desktops: Not Just Nehalem

Intel is intensely focused on getting out its new architecture, code-named Nehalem but officially called the Intel Core i7. It will take some time for Nehalem to percolate throughout the company's product line, however, so the older 45nm Core 2 products will continue to play leading roles through the first half of 2009.

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One reason for the slow rollout is that early Nehalem desktop chips are all quad-core CPUs. Sure, single-core processors have pretty much faded from the scene, but dual-core is still going strong. In September 2008, Intel even boosted the dual-core line, shipping the 3.3-GHz Core 2 Duo E8600. On the other hand, there aren't likely to be a lot of additional shifts in the Core 2 lineup. And entry-level quad-core CPUs, like the Core 2 Quad Q8200 and Q9300, won't be replaced by Nehalem CPUs in the near future.

Of course, Nehalem is the big news, and Intel initially launched three new CPUs: the 2.66-GHz Core i7-920, the 2.93-GHz Core i7-940, and the high-end Core i7-965 Extreme, which clocks in at 3.2 GHz. These new CPUs are substantially improved over the original Core 2 architecture. The most significant enhancements include

• An integrated, on-die memory controller, supporting up to three channels of DDR3 memory. Having the controller on-die improves memory latency, while triple channel access to DDR3 offers massive memory bandwidth.
• Four cores on a single die (previous Intel quad-core CPUs consisted of two dual-core dies in a single package). This improves core-to-core communication when compared with the dual-die configuration in earlier Intel quad-core processors.
• A new system bus, QPI (QuickPath Interconnect), to facilitate all that bandwidth.
• The return of Hyper-Threading, Intel's version of simultaneous multithreading, allowing each core to run two threads for a total of eight threads. This can improve multitasking and increase performance in multithreaded apps.
• A new chipset, the X58, tuned for high-end, enthusiast users.
• A new, 1,366-pin socket called Socket B, or LGA1366; Core i7 is not compatible with the earlier LGA775 socket used in the Core 2 Duo and Core 2 Quad processors. All those extra pins are needed for the on-die memory controller.

Why does Nehalem require a new socket? It's simple: The memory controller is now embedded in the CPU die, so all those pins for moving memory that used to be part of the old MCH (memory controller hub) now need to be integrated into the CPU socket.

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Initial pricing for Core i7 CPUs is pretty aggressive; the 2.66-GHz i7-920 CPU is priced at just $284 in volume quantities. Still, Core i7 will be found mostly in high-end systems, since the initial motherboards will likely be fairly pricey—in the neighborhood of $300 or more. In the second half of the year, however, Intel is prepping mainstream CPUs and chipsets using the new architecture, along with the mainstream Havendale (dual-core) and Lynnfield (quad-core) processors.

Havendale will feature Intel's first attempt at integrating a graphics core on the CPU, though it's not clear at this point whether Havendale's graphics core will actually be on the same die as the CPU or on a second die built into the processor package. The Ibex Peak chipset will integrate the display controller, separating display and graphics into different chips. (Ibex Peak is Intel's next-gen chipset, to go with its new processors. More on that later.)

Lynnfield will be quad-core and will work with Ibex Peak, too, but it won't feature graphics integrated into the CPU. This creates an interesting dichotomy: Intel won't integrate graphics on mainstream desktop systems with quad-core CPUs. In other words, a quad-core Ibex Peak system will require a discrete graphics card, while a dual-core system based on that chipset may have integrated graphics