Intel Core 2 Extreme X6800

Reviewed on 7/13/06    Release date: 7/13/06    AMD, you've had a good run.

Intel announced its line of Core 2 Duo desktop CPUs today. If you're buying a new computer or you're building one of your own, you would be wise to see that it has one of Intel's new dual-core chips in it. The Core 2 Duo chips include not only the fastest desktop chips on the market, but also the most cost-effective and among the most power-efficient. About the only people these new chips aren't good news for are the folks at AMD, who can claim the desktop CPU crown no longer.

We've given the full review treatment to two the five Core 2 Duo chips. You can read about the price-performance champ, the $530 Core 2 Duo E6700 here and the entire Core 2 Duo series here. In this review we'll examine Intel's flagship, the $999 2.93GHz Core 2 Extreme X6800, which is now the fastest desktop CPU you can buy.

As we outlined in a blog post a month ago, the Core 2 Duo represents a new era for Intel. It's the first desktop chip family that doesn't use the NetBurst architecture, which has been the template for every design since the Pentium 4. Instead, the Core 2 Duo uses what's called the Core architecture (not to be confused with Intel's Core Duo and Core Solo laptop chips, released this past January). The advances in the Core architecture explain why even though the Core 2 Duo chips have lower clock speeds, they're faster than the older dual-core Pentium D 900 series chips. The Core 2 Extreme X6800 chip, the Core 2 Duo E6700, and the $316 Core 2 E6600 represent the top tier of Intel's new line, and in addition to the broader Core architecture similarities, they all have 4MB of unified L2 cache. The lower end of the Core 2 Duo line, comprised of the $224 E6400 and the $183 E6300, has a 2MB unified L2 cache.

We won't belabor each point here since the blog post already spells it out, but the key is that it's not simply one feature that gives the Core 2 Duo chips their strength, but rather a host of design improvements across the chip and the way it transports data that improves performance. And our test results bear this out.

The Core 2 Extreme X6800 made a clean sweep of all of our benchmarks. AMD's closest competition, the 2.6GHz Athlon 64 FX-62, came within 5 percent on our iTunes, multitasking, and Microsoft Office tests, but on our Half-Life 2 and our Adobe Photoshop CS2 tests, AMD lost badly, by as much as 28 percent on Half-Life 2. At $999, Intel's new flagship processor might not be as compelling a deal as the only slightly slower $530 Core 2 Duo E6700, but for enthusiasts and others with the passion and the wallet to ensure that they have the fastest chip out there, the Core 2 Extreme X6800 is now it.

But there's even more to the Core 2 Duo story than performance. One of the key elements of the new chips is their power efficiency. We base our findings on a number called the thermal design power (TDP), which is the number that AMD and Intel each provide to system vendors and various PC hardware makers for determining how much power each chip will require, and thus the amount of heat they'll need to dissipate. On Intel's last generation of dual-core desktop chips, the Pentium D 900s, the TDP rating fell between 95 and 130 watts. But because the Core 2 Duo design incorporates power management techniques from Intel's notebook chips, its power requirements are much more forgiving. All but the Core 2 Extreme X6800 have a TDP of 65 watts, while the Extreme chip itself is only 75 watts.

For its own dual-core Athlon 64 X2 chips, AMD tells its hardware partners to prepare for a TDP of between 89 and 110 watts (although its Energy Efficient and Small Form Factor Athlon 64 X2 products, which have yet to hit the market in any quantity, go to 65 and 35 watts, respectively). Intel has caught flack in the past for providing the fan makers with inadequate TDP ratings, which resulted in overly noisy fans for the Pentium D chips that had too spin exceedingly fast to cool the chips properly. But the Falcon Northwest Mach V we reviewed alongside this launch came with stock cooling parts. It will be hard to tell exactly how well Intel's provided specs live up to their real-world requirements until the hardware has been disseminated widely, but that a performance stickler such as Falcon sent the standard-issue cooling hardware suggests that Intel took note of the problems it had in the past.

So what does all that really mean? What it means is that Core 2 Duo makes it easier for PC vendors to design smaller PCs that are just as powerful as their full-size counterparts, because they don't have to deal with as much heat, nor provide massive power supplies and towering heat sinks. Your PC should also run more quietly, since the cooler parts don't need as much work from your system fans. It also means less thermal wear-and-tear. As parts run hotter, the likelihood of their failure increases. The lower the TDP, the happier your PC and its surrounding components.

And as to the surrounding parts, if you already have an Intel-based PC and would like to upgrade, Intel has made it easy. The Core 2 Duo chips use the same Socket LGA775 interface as the Pentium D 900 series. If you have an Intel motherboard using a 965 chipset, you're ready to go with Core 2 Duo and a single graphics card. If you want to run an Intel and dual-graphics config, you have two options. Intel's 975 chipsets support ATI's CrossFire tech only, and if you want to run SLI, you'll need a motherboard in Nvidia's Nforce 500 for Intel series.

Enthusiasts have another point to consider about the Core 2 Extreme X6800; it's the only Core 2 chip whose clock multiplier comes unlocked. This means you can overclock this CPU right out of the box. We haven't tried it ourselves, but we've heard from Falcon Northwest and others that they've been able to clock the chip up to 3.7GHz from its 2.93GHz stock speed. Considering the efficient thermals and the already scary base performance, we have a feeling that you overclockers out there might drive this chip to impressive heights.

For AMD, the outlook isn't great at the moment. Its so-called 4x4 design, which will let you run two Athlon 64 FX-62 chips in a single PC, might overtake a single Core 2 Extreme X6800 on raw performance. Details are scant about 4x4's particulars, but if a single Athlon 64 FX-62 costs about $1,031, two will have you crossing the $2,000 mark on chips alone, not to mention the motherboard, the size of the case, as well as the cooling hardware required to operate it. AMD says it's going to drop prices this month to compete on price-performance ratio. That might make for some compelling desktop deals, but for now Intel boasts the superior technology.

Test bed configurations:

AMD test bed
Asus M2N32-SLI Deluxe motherboard; Nvidia Nforce 590 SLI chipset; 1,024MB Corsair 1,066MHz DDR2 SDRAM; 512MB Nvidia GeForce 7900 GTX; 74GB Western Digital 10,000rpm Serial ATA hard drive; Windows XP Professional SP2; PC Power & Cooling 1Kw power supply

Intel test bed
Intel Desktop Board D975XBX; Intel 975X chipset; 1,024MB Corsair 667MHz DDR2 SDRAM; 512MB Nvidia GeForce 7900 GTX; 74GB Western Digital 10,000rpm Serial ATA hard drive; Windows XP Professional SP2; PC Power & Cooling 1Kw power supply