YOU'VE GOTTA LIKE Intel's Core 2 Duo processors. After struggling mightily with performance and power consumption problems in the latter-day Pentiums, Intel came roaring back with the Core 2 Duo, producing a chip that goes like stink without spinning the electric meter into a frenzy. Since it offers a better combination of processing power, energy efficiency, and overclocking headroom than the Athlon 64, the Core 2 Duo has quickly become an enthusiast favorite, capturing prominent spots in our system guide recommendations and prompting a new round of upgrades for many folks.

Now comes the CPU de grâce, a processor that takes advantage of the Core 2 Duo's modest heat output by cramming two of those chips together into a single socket, a product Intel can plausibly claim is the world's first quad-core CPU. The Core 2 Extreme QX6700 isn't exactly cheap and doesn't run especially cool, but it will turn your spare bedroom into the computing equivalent of a government astrophysics lab and make the neighbors terribly jealous—provided your neighbors are total geeks.

What hath Intel wrought with this quad-core beast? Do four CPU cores make sense in a desktop PC, and what sort of applications can really take advantage of such power? Let's have a look.