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Happy 10th birthday to Intel’s Core 2 Duo

Ten years ago today, Intel launched the Core 2 Duo. The company’s then-new 65nm Conroe core set new records for efficiency and high performance. It gave Intel a serious response to AMD’s Athlon 64 family, which had spent nearly three years making hash of the Pentium 4 — and it set the stage for Intel’s ultimate dominance of the x86 CPU market.

The Core 2 Duo wasn’t Intel’s first dual-core — that was Smithfield, the Prescott P4 chip that debuted the previous year — but it was the first CPU from Intel to show the promise of the dual-core approach that AMD had already debuted. It’s hard to remember now, but back then the cost difference between a single-core and dual-core system was enormous. Not only were the motherboards more expensive, the CPUs themselves often commanded significant price premiums. Quad-core systems were even more expensive, and the handful of boards on the open market lacked the features that enthusiasts wanted, like AGP slots. AMD broke early ground on popularizing dual-core systems, but most people experienced their first dual-core systems on Intel hardware. It was a strong and flexible enough architecture to convince Apple to move away from PowerPC and to x86 — another seismic shift in the industry.

The roots of the Core 2 Duo go back much farther than 2006, though, to the P6 (Pentium Pro) architecture that Intel launched in 1995. Pentium Pro begat Pentium II, which begat Pentium III (Klamath, Coppermine, and Tualatin). After the P3, Intel made the decision to switch to the Netburst architecture and leapt from 2GHz CPUs in January 2002 to 3.2GHz (with Hyper-Threading) on June 23, 2003. That’s a 60% clock speed jump in less than two years, with the addition of simultaneous multi-threading on top of that. AMD, meanwhile, was still flogging the original Athlon core — and while K7 had competed extremely well against early iterations of the P4, Intel’s 130nm Northwood refresh had pumped a heck of a lot of gas into the Pentium 4’s proverbial tank.

The K8 launch in September 2003 proved that AMD’s integrated memory controller and improved architecture could seriously challenge the P4’s supremacy in games and consumer workloads, while the follow-up Pentium 4 core, Prescott, was a hot-running wreck with dramatically lower efficiency and no headroom for the higher clock frequencies that would’ve made up the difference. When dual-core chips debuted, the Athlon 64 X2 made hash of Intel’s P4-based Smithfield. From May 31, 2005 through to July 27, 2006 AMD swept Intel in virtually every benchmark and price point. The Athlon 64 X2 was a better, faster, cheaper, and more power-efficient chip than anything Intel could bring to market. Not coincidentally, this is also when Intel was using rebate payments and compiler optimizations to limit AMD’s performance and market share by any means it could find.

But Intel didn’t just lean on its market position — it invested in a long-term engineering program that became the future of its CPU efforts. The Pentium 4 wasn’t designed for the low-power envelopes that some laptop manufacturers wanted, so Intel built a mobile version of the Pentium 3, dubbed the Pentium M. The Pentium M continued to evolve in the Banias and Dothan CPU cores (Banias was the focus of an incredibly successful Intel branding effort, called Centrino). At every step, Intel focused on building a power-efficient CPU that evolved and became more powerful without sacrificing its intrinsically better power efficiency or execution capabilities. When it became clear that Prescott would never hit its performance or power targets, Intel was caught flat-footed in the short-term — the Pentium M wasn’t ready to take over on the desktop yet. By July 27, 2006, Conroe was — and benchmarks show just how potent the new core was.

Anandtech has a deep dive into the Core 2 Duo’s architecture and capabilities that I highly recommend reading if you want to brush up on how Intel evolved the P6 core and what the long-term ramifications were. Conroe didn’t just sweep the Pentium 4’s performance out of the market — it kicked off a chain of events that left AMD unable to compete against Intel in raw CPU performance.

AMD tried to counter Intel with the first iteration of the Phenom architecture, but Barcelona, which debuted a year later, was a hot, slow-running chip that only modestly improved on K8 and was clock-limited compared with its rival. Its successor, the Phenom II, actually compared fairly well against the Core 2 Duo, but by the time it launched Intel had already moved on to the Core i7 and Nehalem. AMD fought back by launching its Thuban-class processors with six cores, but the tide had turned. Instead of triumphantly re-establishing AMD’s ability to compete with Intel, Bulldozer turned the clock backwards in multiple ways. Since 2012, AMD’s CPU efforts have mostly focused on turning the Bulldozer architecture into something that could actually fit into modern 15-35W laptop form factors, not improving its top-end performance. Zen is targeting a 40% IPC uplift over Carrizo, but it’s not likely to close the gap with Intel in one clean sweep, and it’s not clear if Zen will manage to match Piledriver’s high clock speeds.

In retrospect, Core 2 Duo was the herald of difficult things to come. The signs had been there for years — in late 2004 I wrote an article about using Dothan on a desktop and warned that if AMD didn’t pay attention to the performance Pentium M could put on the board it would leave K8 in a world of hurt. Even so, I didn’t expect C2D to be the beginning of a trend that would leave AMD flatly unable to compete with its rival for nearly half a decade.

Hopefully Zen will be the beginning of reversing that trend, but the graph from Anandtech above shows one other problematic fact — AMD is fighting its way back from the deepest competitive trough that’s ever existed between the two companies. The gap between the top-end Athlon 64 X2 and the top-end Core 2 Duo is much larger today than it ever was back in 2006.

Now read: Intel Core i5 vs. Core i7: Which processor should you buy?

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