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Intel's Core i7-980X Extreme processor


The desktop's first six-core CPU would strike fear into the competition, if it had any
— 11:00 PM on March 10, 2010

I have to tell you, sometimes, being a critical reviewer in the realm of technology is not an easy task. The problem comes down to the sheer rate of improvement among the products we review. If we were Car and Driver, it would look something like this. One year, we'd be reviewing a car that could accelerate from zero to 60 in eight seconds. A year later, we'd be testing a car in the same price range with a six-second 0-60 time. Another year after that, the standard would be down to four seconds. The next year? Three. Soon, pressing the accelerator would subject the driver to forces strong enough to be lethal in the right amounts.

Which is, for a car guy, a barrel of fun.

We have that sort of dynamic going on with computer chips, and it's also quite entertaining, if you're so inclined. I've gone from listening to short programs load in from tape on an Atari 800 to 12-megapixel monitors arrays playing amazing-looking games in full motion. This is not normal in any other walk of life.

Now, don't get me wrong. I can pick nits with the best of 'em. But some days, I'm still amazed that I don't have to listen to a series of bleeps and bloops for 30 minutes before I get to play Borderlands. At times like that, this new processor Intel will be officially introducing soon is almost incomprehensible. The Core i7-980X builds on the foundation established by the first Core i7 processors back in late 2008, but it raises the core count from four to six and adds a bundle of performance in the process. Given this thing's performance and other qualities, I'm having a difficult time finding reasons to complain. Keep reading, and you'll see what I mean.


Gulftown chips on a wafer. Source: Intel.

Introducing Gulftown
If you've been following Intel CPUs lately, you're probably well-versed in code names. Knowing them is helpful because the complexity of Intel's product portfolio is surpassed only by that of its naming scheme. Consequently, we've started referring to Clarkdale, Lynnfield, and Bloomfield rather than attempting to enumerate all possible products based on those bits of silicon. The Core i7-980X adds a new code name to that constellation: Gulftown.

Like the dual-core Clarkdale Core i3/i5 processors introduced earlier this year, Gulftown is a part of the Westmere family of 32-nm chips. This six-core processor is primarily known, in its server/workstation guise, as Westmere-EP; Gulftown is the code name for the desktop variants of the chip. Gulftown is intended to be a drop-in replacement for the existing members of the Core i7-900 series, all of which are based on the quad-core chip code-named Bloomfield.

If your head hasn't exploded yet from code-name overload, I congratulate you. The main things you need to know about Gulftown are reproduced in the table below, which should act as something of a code-name decoder.

Code name Key
products
Cores Threads Last-level
cache size
Process node
(Nanometers)
Estimated
transistors
(Millions)
Die
area
(mm²)
Penryn Core 2 Duo 2 2 6 MB 45 410 107
Bloomfield Core i7 4 8 8 MB 45 731 263
Lynnfield Core i5, i7 4 8 8 MB 45 774 296
Westmere Core i3, i5 2 4 4 MB 32 383 81
Gulftown Core i7-980x 6 12 12 MB 32 1170 248
Deneb Phenom II 4 4 6 MB 45 758 258
Propus/Rana Athlon II X4/X3 4 4 512 KB x 4 45 300 169
Regor Athlon II X2 2 2 1 MB x 2 45 234 118

Compared to Bloomfield, Gulftown has 50% more cores and cache, yet it fits into the same basic power envelope at the same clock speed. Gulftown packs substantially more transistors into a smaller die area than Bloomfield, too. All of this magic comes courtesy of Intel's new 32-nm chip fabrication process, which combines second-generation high-k + metal gate transistors with first-generation immersion lithography.

A map of the Gulftown die. Source: Intel.

The image above shows Gulftown's layout nicely. As a drop-in replacement for Bloomfield, Gulftown has no integrated PCI Express connectivity (a la Lynnfield) and no integrated graphics (a la Clarkdale). Instead, it relies on a QuickPath Interconnect to link it to the X58 chipset.

Interestingly, Intel's architects call the uncore area running up the center of the chip "the tube." (Well, I thought it was interesting, anyway.) Your eye may also be drawn to the top left corner of the chip, where there's a pretty big area with not much going on. In a briefing, Dave Hill, Westmere's lead architect, acknowledged this "white space" and noted only that he wasn't going to talk about the reasons for it. Presumably, Intel would want to minimize wasted space on a design like this one, so I'm intrigued. Almost looks to me like one could eliminate the apparent white space on both sides of the memory controller and the I/O, uncore, and memory controller would wrap pretty snugly around four cores their associated L3 cache. As far as we know, though, Intel has no plans to release a native quad-core derivative of Westmere. Instead, the firm will press ahead with a quad-core version of Sandy Bridge, the upcoming architectural refresh slated for the 32-nm process.

Speaking of which, the chips in the Westmere family are a "tick" in Intel's vaunted tick-tock cadence. They're a refinement of the quad-core Nehalem architecture introduced at 45 nanometers, with a relatively conservative set of enhancements outside of the obvious changes in core counts and cache sizes. Sandy Bridge will be a "tock" with more radical architectural remodeling. Still, the same Oregon-based team that created Nehalem also did Westmere, so the ins and outs of the processor were already familiar to them. They couldn't resist making a few tweaks along the way. Most notable among them is the addition of seven new instructions tailored to accelerate the most common data encryption algorithms.

Another improvement, carried over from the Lynnfield Core i5/i7 chips, is the addition of a gate that can cut off power to most elements of the "uncore" when the chip is idling in its lowest sleep states, substantially reducing power consumption and even leakage power. This provision extends the power gate concept first implemented in Nehalem processors. Gulftown has seven power gates, one for each core and one for the uncore. Not all elements of the uncore are affected by the power gate. Notably, the chip's built-in power management processor isn't shut off, for obvious reasons. Meanwhile, the memory controller, QuickPath Interconnect, and L3 cache have their voltage reduced to "retention levels." The chip's architects say there's no substantial increase in the time required for the CPU to wake up from its deeper sleep states.

Other Westmere changes are perhaps even more esoteric. The APIC timer now remains running all of the time, even during sleep. Large pages, up to 1GB in size, are now supported, and some improvements have been made for the sake of virtualization performance. Despite the presence of more and larger caches, the data pre-fetch algorithms for the caches remain the same.

One other modification in Gulftown will please folks trying to achieve higher memory clocks. With Bloomfield, the maximum memory speed is half the uncore frequency. As a result, Bloomfield's uncore must run at 4GHz in order to accommodate 2GHz DIMMs. Like Lynnfield, Gulftown's uncore only needs to run at 1.5X the max memory speed, so 2GHz memory frequencies are possible with the uncore at 3GHz.