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Intel's Core 2 Extreme QX6850 processor

It's fast, even if we're not

Intel's Core 2 Extreme QX6850 processor said its first hello to the world some months ago, and unusually, I totally whiffed on getting my review out at that time. In my defense, I had many things on my mind, including preparing for the launch of brand-new processor microarchitectures from AMD and Intel in the form of the Barcelona Opterons and Harpertown Xeons. Meanwhile, I was rebuilding our desktop-class CPU test rigs with new software and hardware, the latest and greatest stuff. I was also busy with utterly ruining my website, and let me tell you, personal career suicide isn't as easy as Britney Spears makes it look. Girl has a gift.

At any rate, I've finally finished my first round of tests with our all-new test setup, and we can now show you how Intel's fastest quad-core desktop processor, the Core 2 Extreme QX6580, stacks up against a range of competitors—everything from the new Athlon 64 X2 6400+ to dual-socket monsters like AMD's Quad FX and Intel's V8 platform, just because we can. And, of course, we have new applications and the latest games, like BioShock and Team Fortress 2, in the mix. Keep reading for a cornucopia of quad-core goodness—but read quickly, before Intel replaces this CPU with a 45nm Penryn-based chip.

The QX6850 in situ. Look it up.

The dirt on the QX6850
Here are the vitals on the Core 2 Extreme QX6850. This processor is yet another spin on Intel's Kentsfield quad-core product, which incorporates two Core 2 Duo chips onto a single package for a quartet of bit-flipping goodness. Like other Kentsfield-based products, it has a total of 8MB of L2 cache, or 4MB per chip. The QX6850 distinguishes itself from its direct predecessor, the QX6800, with the addition of a 3GHz core clock frequency and a 1333MHz front-side bus. Intel has moved the bulk of its Core 2 lineup to this higher bus speed, whose benefits we first tested in our review of the Core 2 Duo E6750. At that time, we concluded that a 1333MHz front-side bus wasn't much help to a dual-core processor, but it might be more of a boon to a quad-core part, especially because the two chips on Kentsfield processors communicate between themselves via this bus.

At this point, the reader should feel drama and tension rise.

So we'll have to see whether the faster bus offers more benefit for the QX6850.

Intel's Core 2 processors have also learned a new trick in recent months: lower power consumption and heat production, thanks to the chips' new rev-G stepping. The QX6850 houses a couple of rev-G chips, which is one reason why it can accommodate higher clock and bus speeds while fitting into the same thermal envelope as the QX6800.

Sounds good, right? Yes, but this is technology, and things move quickly. Intel is set to replace its 65nm Core 2 processors with "Penryn" based products fabbed with its new 45nm process in, like, days. That means the QX6850 is the last of its breed, destined to live the final 15 years of its career playing to half-filled theater audiences in Vegas.

I have no idea what that means. Work with me here.

I should mention that the Core 2 Extreme QX6850 currently sells for somewhere between $1100 and $1300 at online retailers, which is enough money to buy you several range-top microwave ovens and an iPhone. The range-top ovens and iPhone couldn't easily be replaced by a $280 Core 2 Quad Q6600 processor, either. Then again, neither the phone, the microwaves, nor the Q6600 have an unlocked upper multiplier for easy overclocking.

Heck, the iPhone is locked down tighter than Fort Knox.

Intel's Core 2 Extreme processors, though, make overclocking a snap. These high-end quad-core "halo products" also have no true competition right now, unless you count AMD's Quad FX platform. We've tested it here, for what it's worth, but I'll save you some suspense: the QX6800 was already faster than Quad FX.

We've also tested AMD's new fastest dual-core processor, the Athlon 64 X2 6400+ Black Edition, distinguished by its black box, limited quantities, and modest debut. We couldn't let this one slip by under the radar entirely, even if it's not AMD's proudest achievement.