Intel Core 2 Extreme X6800 review

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 130W. But because the Core 2 Duo design incorporates power management techniques from Intel's laptop chips, its power requirements are much more forgiving. All but the Core 2 Extreme X6800 have a TDP of 65W, while the Extreme chip itself is only 75W.

For its own dual-core Athlon 64 X2 chips, AMD tells its hardware partners to prepare for a TDP of between 89 and 110W (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 35W, 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 to spin exceedingly fast to cool the chips properly. But the Falcon Northwest Mach V desktop, for example, 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 the fact that a performance stickler like 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 overclockers 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 (£544), two will have you crossing the £1,000 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

Edited by Matthew Elliott
Additional editing by Kate Macefield