Tests show that Intel's first quad-core chip, the 2.66-GHz Core 2 Extreme QX6700, should bring impressive speed boosts to complex video-editing and 3D-rendering work. But while you might think that since two cores are good, four cores will be twice as good for all your computing tasks, our exclusive tests of the new chip tell a different story.

Although PCs with the new quad-core chip (formerly code-named Kentsfield) offer plenty of speed, our tests reveal that many users will get more bang for their buck by sticking with Intel's other Core 2 Extreme chip, the 2.93-GHz, dual-core X6800. For the same US$999 price, the X6800 chip offers just a bit more clock speed than the 2.66-GHz QX6700 does, and with few mainstream applications tuned to take advantage of four or more CPU cores, the extra clock speed provides a real performance advantage on most tasks. Systems with the new chip should be available this month.

Graphics speed

We looked at a preproduction QX6700 chip in a reference system with a preproduction D975XBX2 motherboard and our standard set of components, including 2GB of DDR2 memory, a pair of SATA hard drives configured in a striped array, and an nVidia GeForce 7800GT-based graphics card. We also looked at three high-end, fully decked-out commercial systems -- the Alienware Area-51 7500 (US$4,479), CyberPower Gamer Infinity 1950 (US$3599), and Xi MTower IGE (US$4,149) -- equipped with the quad-core processor. We then compared these systems with previously tested reference PCs as well as with an Extreme X6800-based CyberPower Gamer Infinity SLI Ultra and a 2.67-GHz Core 2 Duo E6700-based Dell XPS 700.

As our previous tests have shown, systems with the dual-core Extreme X6800 provide blazing performance. It's still the faster chip for single-threaded apps, such as familiar Office productivity programs. It also holds the advantage in the multitasking test we use in our WorldBench 5 suite: The reference PC with the X6800 finished in 279 seconds compared with 292 seconds for the system with the quad-core chip. Systems with Kentsfield scored nearly identically to a same-speed Core 2 Duo on standard productivity apps, which is unsurprising since Kentsfield is essentially a pair of linked Core 2 Duo dies on one chip.

Results from the commercial systems generally mirrored those of the reference PCs. The quad-core Alienware Area-51 7500 system stood out a bit because it nearly matched the Core 2 Extreme X6800-based CyberPower PC on our two Adobe graphics tests and our gaming test, and edged slightly ahead on our Nero Express test.

The new chip really starts to shine with programs that can take advantage of its four cores, such as video and 3D editing software. We ran several video and 3D editing tests on a quad-core chip at an Intel preview event and, though we didn't confirm these results in our lab, we saw some dramatic speed improvements -- around 80 percent in POV-Ray 15, a 3D scene-rendering app, and 33 percent in Sony's Vegas 7.0a video editor.

Bottom line

These preliminary performance results support Intel's decision to roll out the quad-core chip as a CPU for enthusiasts first. While gamers won't see many immediate gains from going quad-core, next year's Alan Wake and Unreal Tournament 2007 will support multithreading (a few current games have patches that provide only limited support for multithreading), making it a fair investment. And anyone working with video or 3D rendering should get significant boosts right away.

As more games and mainstream programs begin to take advantage of multiple CPU threads, and as video editing and video sharing continue to grow in popularity, more and more people will see real benefits from multiple CPU cores. In the first half of next year, new Core 2 Quad chips (as Intel is officially referring to the new quad-core line) should supply that power, beginning with a 2.4-GHz CPU running on the 1066-MHz bus. Intel also plans to launch quad-core versions of its workstation- and server-focused Xeon line before year's end as well.

Meanwhile, AMD intends to release its dual-socket 4x4 platform, its own two-chip quad-core offering, before the end of the year.