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Intel's Core 2 Duo and Extreme processors

Conroe at last

INTEL'S DESKTOP PROCESSORS HAVE NOT been in a good place for the past two and a half years. Pentium 4 and Pentium D CPUs have run at relatively high clock speeds but delivered relatively low performance compared to their competition from AMD. They've also drawn a tremendous amount of power, which they've generously expended as heat. In other words, they've been hotter than Jessica Simpson and slower than, well, Jessica Simpson. Despite heroic efforts by Intel's engineering and manufacturing types, these chips based on the Netburst microarchitecture haven't been able to overcome their inherent limitations well enough to keep up with the Athlon 64. As a result, Intel decided to scrap Netburst and bet the farm on a new high-performance, low-power design from the Israel-based design team responsible for the Pentium M.

The product of that team's efforts is a new CPU microarchitecture known as Core, of which the Core 2 Duo and Core 2 Extreme are among the first implementations intended for desktop PCs. We've been knee-deep in hype about the Core architecture for months now, with a stream of juicy technical details, semi-official benchmark previews, and clandestine reviews of pre-release products feeding the anticipation. Clearly, when a player as big as Intel stumbles as badly as it has, PC enthusiasts and most others in the industry are keen to see it get back up and start delivering exciting products once again.

Fortunately, the wait for Core 2 processors is almost over. Intel has decided to take the wraps off final reviews of its new CPUs today, in anticipation of the chips' release to the public in a couple of weeks. Fish have gotta swim, politicians have gotta dissemble, and TR has gotta test hardware, so of course we've had the Core 2 processors on the test bench here in Damage Labs for a thorough workout against AMD's finest—including the new Energy Efficient versions of the Athlon 64 X2. After many hours of testing, we're pleased to report that the Core 2 chips live up to the hype. Intel has recovered its stride, returned to its winning ways, gotten its groove back, and put the izzle back in its shizzle. Read on for our full review.

Conroe up close
We first previewed the chip code-named Conroe back in March, and now we finally have our hands on one within the confines of our own labs. In spite of all the hype, the Core 2 Duo processor itself is a rather unassuming bloke that looks no different than Pentium CPUs that preceeded it. Like them, it resides in an LGA775-style socket and runs on a 1066MHz front-side bus.

The Core 2 Duo E6700 processor Also like its most immediate predecessors, the Core 2 Duo is manufactured on Intel's 65nm fab process. Unlike them, however, the Core 2 Duo is not comprised of two chips crammed together on one package; it's a native dual-core design with a total of roughly 291 million transistors arranged in an area that's 143 mm2. By contrast, each of the Pentium Extreme Edition 965's two chips have an estimated 188 million transistors in an 81-mm2 die. If you add the two chips together, the Pentium Extreme Edition 965 has more total transistors and a larger total die area than the Core 2 Duo.

Intel plans to offer five flavors of Core 2 processors initially, with prices and features like so:


Clock speedBus speedL2 cacheTDPPrice
Core 2 Extreme X68002.93GHz1066MHz4MB75 W$999
Core 2 Duo E67002.67GHz1066MHz4MB65 W$530
Core 2 Duo E66002.4GHz1066MHz4MB65 W$316
Core 2 Duo E64002.13GHz1066MHz2MB65 W$224
Core 2 Duo E63001.86GHz1066MHz2MB65 W$183

The prices on the mid-range models are quite reasonable once you consider performance, as we'll do shortly. What you'll really want to notice about the Core 2 chips, though, is the column labeled TDP. This parameter—thermal design power—specifies the amount of cooling the chip requires, and the numbers are down dramatically from the Pentium Extreme Edition 965's rating of 130W. Clock speeds are down, as well, since the Core microarchitecture focuses on achieving high performance per clock rather than stratospheric clock frequencies. The fastest Core 2 processor is the X6800 Extreme, which is separated from the regular Core 2 Duos only by its 2.93GHz clock speed and a 10W higher TDP—oh, and by almost half a grand.

Intel says complete PC systems based on the Core 2 Extreme X6800 and individually boxed products will both begin selling on July 27th, while Core 2 Duo processors with 4MB of L2 cache should show up on August 7th. Intel will be transitioning its CPU production gradually away from Pentiums to Core 2 Duos, and that transition might not happen as quickly as the market would like. I wouldn't be surprised to see strong demand and short supply of these processors for the next couple of months, until Intel is able to ramp up production volumes. The less expensive versions of the Core 2 Duo with 2MB of L2 cache are initial casualties of this controlled ramp. They aren't expected to be available until the fourth quarter of this year.

On a brighter note, the supporting infrastructure for Core 2 chips is already fairly well established. The processors should be compatible with a number of chipsets, including the enthusiast-class 975X and the upcoming 965-series mainstream chipsets from Intel. NVIDIA's nForce4 SLI X16 Intel Edition should work, too, as well as the yet-to-be-released nForce 500 series for Intel. In fact, the Core 2 can act as a drop-in replacement for a Pentium D or Pentium Extreme Edition, provided that the motherboard is capable of supplying the lower voltages that Core 2 processors require. Only the most recent motherboards seem to have Core 2 support, so you'll want to check carefully with the motherboard maker before assuming a board is compatible. Our Core 2 Duo and Extreme review samples, for example, came from Intel with an updated version of the D975XBX motherboard, since older revisions couldn't supply the proper voltage.

Speaking of which, the upgrade path for those who buy motherboards for Core 2 processors in the next few months isn't entirely clear. The server/workstation version of the Core microarchitecture, the Woodcrest Xeon, already rides on a faster 1333MHz front-side bus. The Core 2 Duo may move to this faster bus frequency at some point, but Intel hasn't revealed a schedule for this move. Intel has revealed plans to deliver "Kentsfield," a quad-core processor with two Conroe chips in a single package, in early 2007, but we don't yet know whether current motherboards will be able to support it. Investing in a Core 2-capable motherboard right now might be a recipe for longevity, but it might also be a dead end as far as CPU upgrades are concerned.

What's with the name?
Before we go on, we should probably take a moment to talk about the Core 2 Duo product name. It's dreadful, of course, but for deeper reasons than you might think. You see, microprocessors tend to be known by several names throughout their lives, and usually those names aren't really related. For example, the chip code-named Willamette, based on a microarchitecture called Netburst, became the first product known as Pentium 4. The multiple names may be a little difficult to keep straight, but they're distinctive and follow a coherent logic.

This chip, however, is different. The microarchitecture is called Core, the chip is code-named Conroe, and the product is called Core 2 Duo. By that logic, the chip code-named Willamette would have been based on the Willette microarchitecture, and the first product might have been the Willette 4 Quadro, which everyone knows is actually a disposable razor.

The Core 2 Duo's name does make sense from a certain perspective, though, because Intel has been shipping the original Core Duo as a dual-core mobile processor since the beginning of the year. There's also a single-core version of that processor known as the Core Solo, which explains the whole Duo suffix. And the mobile version of the Core 2 Duo, based on the chip code-named Merom, will be the follow-up to the Core Duo.

See? Ahh.

So why name the microarchitecture Core? You've got me. The Core microarchitecture is a descendant of the one found in the current Core Duo, but it's been pretty extensively reworked and certainly deserves a new name. The fact that its name matches up with the previous-gen product's name is confounding. We'll simply have to, as one Intel employee admonished at the Spring '06 IDF, "Deal with it."