Introduction

Up until a few years ago, clock speed was the number one barometer used by many to judge a CPU’s performance. It was a pretty simple formula: higher CPU clock speeds means better performance. With their Netburst Pentium 4 architecture, Intel in particular was shooting for breakthrough clock speeds. Intel had hoped to eventually hit 10GHz with Netburst. As you all certainly know by now though, Intel’s plans for Netburst were never fully realized; ultimately the Pentium 4 never hit 4GHz.

While clock speed is certainly still important today, both AMD and Intel have realized that clock speed isn’t everything. After all, both companies have hit brick walls in frequency scaling with their CPU architectures in the past. This dilemma presents an interesting challenge to both companies – how do you dramatically improve CPU performance without relying on hitting higher clock speeds? The answer both have come up with is simple: integrate more processing cores into the CPU’s die. With two CPUs built into the same CPU die, the CPU can perform twice the amount of work as a conventional single-core CPU.

That’s the theory at least. Of course by now we all know that you’ve got to have software that’s capable of taking advantage of that second processing core, or else it ends up spending most of its time idling.

In 2005, dual-core processing was all the rage. Both AMD and Intel introduced CPUs with two processing cores built-in to the CPU. Initially there was a dearth of software capable of taking advantage of dual-core, but over the course of the past 12 months slowly but surely dual-core software has been steadily trickling in, particularly when it comes to audio/video encoding and 3D rendering.

Kentsfield: Two cores inside

Now in 2006 we see the debut of the first quad-core CPUs. Intel’s first out of the gate with today’s launch of the Core 2 Extreme QX6700, previously known by its codename “Kentsfield”. Intel had originally planned to release the Core 2 Extreme QX6700 in the first quarter of next year, but decided to move the release up by a few months to make it in time for the holidays.

By the end of the first half of next year, AMD plans to release their first quad-core CPU codenamed “Barcelona” (it has also been referred to previously as K8L), but until then they plan on relying their upcoming 4x4 platform. AMD’s 4x4 technology is expected to be released later this month, but it isn’t a quad-core CPU. Instead 4x4 is composed of two dual-core processors.

Ultimately with a 4x4 system you’ve still got four processing cores, but its spread across two processors and thus you’ll need a two-socket motherboard. (AMD can’t affordably integrate four processing cores into one CPU die until their smaller 65-nm manufacturing process is ready.) With Intel’s Core 2 Extreme QX6700, you’ve got four processing cores inside a single socket, in fact the QX6700 is compatible with most of today’s existing Core 2 motherboards…