Nehalem Primer: What We Know So Far About Intel's Next-Gen Penryn Killer

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We’ve been calling Intel’s next-generation CPU family code-named Nehalem a Penryn-killer because, sadly, AMD’s best and brightest have hardly been that. For those who haven’t sifted the sands of the Internet, and picked the brains of OEM’s and hardware vendors for every detail of Intel’s next-gen microarchitecture, here’s your quick primer on Nehalem that’ll make you big man on campus at the next geekfest.

How Many Cores?

Most Nehalem’s will be native quad-core with all four compute cores on the same physical die. Intel says that the design of Nehalem will also let the company build an eight-core version, codenamed Beckton, for servers. Intel also hasn’t ruled out the possibility of a multi-chip version so could perhaps see a double-die Beckton with 16 cores as well.

HyperThreading Returns

An improved version of HyperThreading will find its way into the core of Nehalem. This improved simultaneous multi-threading, or SMT, will let the OS see a quad-core chip as eight cores. Although some still debate its merit, the implementation of HT in the Pentium 4 generally added 15 percent more performance in multi-threaded applications.

Integrated Memory Controller

Nehalem will integrate Intel’s second attempt at an integrated memory controller. The first IMC from Intel was with the ill-fated Timna CPU in the 1990s that cratered when the “PC as cell-phone idea” imploded with the dot-com bust. The IMC in Nehalem will be on-die and DDR3 for consumer CPUs. Beckton, the server-flavor of Nehalem, will continue to support fully buffered DIMMS and their ability to run metric ass-loads of RAM.

In addition to integrating the new IMC, Intel will finally ditch the front-side bus which forces all cores to share data along a shared bus. Instead, Intel will introduce its QuickPath Interconnect that connects all cores with dedicated paths. QPI was previously code-named CSI. Is Intel bashful about adopting two of the key ingredients used in Athlon64/Opteron? Nope. Intel says basically that yeah, they may look the same, but ours is way, way better so that makes it OK. In reality, does it matter who came up with the idea? To us, it’s who can make it faster.

Triple-Channel DDR3

Motherboards for Bloomfield will be a bit crowded thanks to the tri-channel DDR3 layout. As you can guess, you would need to populate three independent channels to get the tri-channel setup. Some boards may feature up to six DIMMs, while others may choose five slots – Three would be populated for tri, and you would have two free slots for additional RAM.

Socket Shuffle

All three Bloomfields will be based on the new LGA1366 socket that is completely incompatible with current LGA775 motherboards. Sometime next year, a value version of Nehalem using a different LGA1160 socket will hit the market. Codenamed Lynnfield, the chip will feature dual-channel DDR3 support instead of tri-channel. The big question is whether Intel will maintain a performance LGA1366 alongside the mainstream LGA1160 product or will LGA1366 get quickly put to rest the way AMD killed the original Socket 940 product in favor of the more mainstream Socket 939.

All indications are that Intel would do exactly that, since OEM’s don’t particularly like having to build two totally different machines. Many prefer to have a single SKU that can be sold as either a mainstream box or a performance machine based on a simple CPU swap out. Going from a mainstream LGA1160 machine to a “performance LGA1366” would mean swapping the motherboard out which means time taken to build the machine and less money in the pocket. However, since Bloomfield shares the same socket with the workstation version (codenamed Gainsetown) there is a possibility that Intel will keep the top-end Bloomfield in business to use as a foil against a possible resurgence by AMD.

How Will Nehalem Perform?

Early reports of Nehalem’s performance is quite good, with some sources telling us that Bloomfield is to Penryn as Conroe was to Prescott. That’s a pretty amazing speed bump, but we must point out that we’ve long thought that Penryn was being sandbagged. With many of the quad-core Penryn’s seemingly capable of running at or near 4GHz and most of the dual-core parts running beyond 4GHz, we’ve long suspected that Intel decided to keep the speeds of Penryn down to keep the yields up. With Bloomfield nearly here, true conspiracy nuts may also wonder if keeping Penryn slow wasn’t a plan to make Bloomfield look even better at launch. It’s not that Bloomfield won’t be fast, but keeping Penryn’s speeds down make the little bars for the next-gen chip look even better.

Availability and Configurations at Launch

The Nehalem CPUs intended for consumers will be offered in three different trims this fall under the Bloomfield codename: A performance chip in excess of 3GHz in the “Extreme” category, a performance version in the 3GHz range, and a mainstream version in the 2.5GHz range. Reported prices map directly onto Intel’s high, mid, low paradigm in use for Penryn.

The top-end chipset for Bloomfield will be called X58. Thanks to Intel and Nvidia burying the axe (although we’re not sure what limb the axe went into) some X58 boards will be the first desktops boards support both SLI and CrossFireX. This will be done by Nvidia selling motherboard makers nForce 200 chips that they can integrate into the boards to “enable” up to tri-SLI support on the boards. Because the deal was very last minute, not all X58 boards may have the chips. Be sure to plan carefully if you want SLI on your X58 machine.

Stay tuned to this page for updates as we find out more about Nehalem!

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