Out with the old and in with the new -- it's almost time to toss out those LGA775 motherboards, as Intel prepares for the official release of its LGA1366 desktop platform for the Core i7 processor. An updated platform base is certainly nothing new for Intel; the company has more active chipsets than AMD has processors. But this is not just another incremental CPU/chipset release. The i7, perhaps still better known by its old codename "Nehalem," represents the architecture that will take Intel into the next decade.

This Is Not Your Father's Core 2

To be fair, the LGA775 socket has been around since mid-2004, almost forever by Intel standards. The Nehalem's larger dimensions, thanks to additions such as an AMD-style on-chip memory controller, dictated a new package. To begin the LGA1366 era, Intel is going high-end, offering an enthusiast-level X58 chipset to go with a high-speed Core i7 processor.

Nehalem represents a new microarchitecture for Intel, but it's built on the same 45-nanometer process as today's "Penryn" models, and will be introduced in dual-, quad-, and eight-core versions. While not a radical departure from existing Core 2 CPUs, there are noted changes. The Core i7 features 64K of Level 1 cache (32K apiece for data and instructions) and 256KB per core of Level 2 cache, along with up to 8MB of Level 3 cache shared between all the cores.

Intel has effectively split the processor into two distinct parts, with one representing the actual core resources while the other houses the L3 cache and onboard memory controller. As a native multicore design, with all of the processor cores on the same die instead of squeezing two or more dies onto one package, the i7's larger internal pathways will automatically increase performance and throughput.

Another Nehalem feature is the return of simultaneous multithreading (SMT), which we and Intel used to call Hyper-Threading. HT technology allows a single processor core to handle two software threads, allowing a dual-core to support four and a quad-core to handle eight threads simultaneously.

They can't match the power of a true extra core, but past Hyper-Threading designs have improved multithreading performance by 15 to 25 percent. This technology has made a comeback with the popular Atom processor, equipping the tiny netbook CPU with enhanced multitasking.

The impact of simultaneous multithreading should be even greater on Nehalem, as the processor has both serious memory bandwidth and an internal architecture tuned for the type of resource-sharing that SMT requires. Intel could have instituted SMT on current Core 2 processors, but felt the architecture was not quite ready. Nehalem performance levels are reported to be noticeably higher than Penryn at a lower relative power usage, and Hyper-Threading will be the cherry on top.

Three New Channels Go Live

The onboard memory controller of the Core i7 platform supports the de facto single and dual-channel DDR3 architecture, but adds a new wrinkle: triple-channel memory. This announcement lit up some eyes in the enthusiast community, and although Intel has been quiet in terms of performance results, demo sessions have yielded some very impressive visual scores.

The first Nehalem iteration is rumored to implement a triple-channel DDR3 architecture, and now that the CPU determines the memory type, speed, capacity, and number of modules, this is going to put some limitations on both motherboard vendors and end users. For example, existing DDR3 memory kits are sold in a dual-channel format, with two modules. The Intel X58 requires three modules for top performance, and many potential upgraders are waiting for memory manufacturers to introduce their triple-channel kits, featuring a trio of fully matched and guaranteed DDR3 sticks.

The presence of an integrated memory controller also means that the Northbridge components of the X58 chipset will be greatly simplified. Intel will even release a Core i7 processor with an integrated graphic core, further limiting the role of the chipset in this new architecture. The Nehalem also marks the debut of Intel's QuickPath Interconnect, with each bidirectional link supplying up to 12.8GB/sec of bandwidth each way for a total bandwidth of 25.6GB/sec per link -- that's over 50GB/sec for the top-end models that will have two QuickPath links.

The X58 Goes Native SLI

With the Nehalem taking over many of the conventional chipset duties, some may view the Intel X58 release as a non-event. But Intel still had a surprise up its sleeve, and the biggest Core i7 news was a bombshell NVIDIA dropped at its Nvision '08 conference. There, the graphics giant confirmed that the Intel X58 would be the first chipset not part of NVIDIA's own nForce line with native support for the NVIDIA SLI multi-GPU technology. This is huge news, as now power users will be able to select a top-of-the-line Intel enthusiast platform that supports not only SLI, but AMD's corresponding CrossFire configuration as well. This is the stuff enthusiast dreams are made of.

The Intel X58 will also support a wide range of SLI configurations with fewer limitations than were initially rumored. Dual-card SLI is available in a PCI Express x16/x16 configuration, while moving to a three- or four-card setup will entail running the extra cards on PCI Express x8 lanes. Of course, this is a bit less than a dedicated nForce 200 chip will offer, with its full-speed x16 lanes for the third and fourth graphics cards.

Even so, adding SLI support for an Intel chipset represents a quantum shift for NVIDIA and its view of the platform world. Previously, it was NVIDIA's way or the highway -- you either needed an nForce chipset or needed to buy a rare, ultra-expensive Intel Skulltrail platform with an onboard nForce 200 chip. Neither was a real solution for SLI fans who also wanted an Intel chipset.

The Intel X58 solves this dilemma, and even though there's reportedly no nForce platform for Nehalem coming soon, it still makes NVIDIA look a little worried in the face of CrossFire's almost total platform coverage.

But this doesn't mean that NVIDIA will allow just any motherboard with an X58 chipset to get SLI certification. The company will continue to administer the program and specify which motherboards get the SLI seal of approval, with not just a rubber stamp but NVIDIA making an explicit decision whether to allow a vendor to enable SLI in the chipset hardware without it.

Intel's upcoming Core i7 microarchitecture seems to have it all -- native multicore design, high-end performance, scalability, a killer feature set, and an insane amount of CPU and memory bandwidth. But as good as Nehalem is, the X58 may be just as important. It's hard to describe the jump in enthusiast interest since the SLI announcement. The prospect of a high-end Intel platform permitting a choice of multiple NVIDIA or multiple ATI graphics cards has been a dream for years now, and to see it finally realized is very exciting. At least to everyone but AMD.