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HardwareZone's 10th Anniversary Special

10 Years of CPU Progression - Part 3: Counting Cores

10 Years of CPU Progression - Part 3: Counting Cores

What was to follow was that the clock speed race turned into a race to fit as many processing cores on a single die as possible. Intel went back to the drawing board and took a different route from NetBurst and the clock obessed Pentium 4. Returning to the Pentium III and in particular, the Pentium M chips that had been derived from the last Pentium III core, Tualatin and found in the company's mobile Centrino platform. Intel's Israeli outfit spearheaded the development of the new architecture, which would feature dual-cores and a return to a less complex 14-stage instruction pipeline. Most importantly, this new Core architecture would have significantly lower power consumption compared to the Pentium 4.

AMD obviously was on the same track, though they were building on its existing K8 series while working on its next generation architecture. It followed up its Athlon 64 with the Athlon 64 X2, which had two Athlon 64 cores on the same die package. This was in late 2005. Intel however had a stopgap measure available earlier that year, featuring a dual-core Pentium D (Smithfield), which was still based on the NetBurst micro-architecture and was basically two 64-bit Prescott cores side by side on the same package.

The main event however was yet to come but in July 2006, Intel finally lifted the wraps off its new Core 2 processors. Before the official product launch, there has been quite a lot of buzz about the new Core micro-architecture and its introduction at IDF Spring 2006 had enthusiasts awaiting Intel's return to form. The new processors, consisting of five Core 2 Duo CPUs - ranging from 1.86GHz to 2.67GHz, with a Core 2 Extreme at 2.93GHz - were all based on the 65nm Conroe core, with between 2MB to 4MB of L2 cache and significantly, had a maximum TDP rating of only 65W (75W for the Extreme version). Suffice to say, its performance more than lived up to its billing and with lower power consumption than any competing AMD processor, the Core 2 brand was off to a great start.

 Back when it was new, the E6300 model of the Core 2 Duo series as shown here was the most famous of the lot because of its high overclocking potential. Even we've dedicated an overclocking article on it.

This lead that the Core 2 processors had over its market rival would be maintained up to its present iteration. Intel spared no time to expand its initial desktop range, with a lower-end Allendale core (lower clock speeds and lesser L2 cache), the single core Conroe-L for the Celeron brand and naturally, given its power efficiency, the Merom core was created for the Centrino platform. The server space meanwhile had Woodcrest to aid the Xeon against AMD's Opteron. Further highlighting its resurgence, Intel launched its first quad-core processor, Kentsfield at the end of the year. This quad-core was made up of two Core 2 Duo processors on a single die package, rather than four discrete cores. While performance benefits vary depending on the nature of the applications, power consumption were similar to doubling that of a Core 2 Duo. Overheads and bandwidth issues also make it less than ideal but AMD then current processors were unfortunately still on 90nm for most of 2006 and were hence unable to compete in terms of power efficiency and performance.

Those who favored AMD however were anticipating the company's next micro-architecture, the K10. These would be quad-core processors that would be available in the middle of 2007 for the Opteron server market before the consumer versions later in the year. AMD was in dire need of these reinforcements, since the Core micro-architecture based Woodcrest was making a great impression and looked capable of quickly retaking the gains made by Opteron in the past few years.

It was also in 2007 that Intel started to implement its tick-tock model of microprocessor development. Also known as Silicon Cadence, this was a rigorous schedule of following every architectural revision with a shrinking of the process technology. In this case, tick referred to the shrinking while tock was a new micro-architecture, with either one happening once in a year. Such an ambitious time frame was probably only possible with a company of Intel's resources and so far it has been executing this on time. For instance, following the 65nm Core 2 processors in mid-2006, Intel was gearing up for its transition to 45nm and was able to give previews of these new 45nm Penryn processors at IDF Spring 2007.

AMD's Barcelona Core Arrives but Core 2 still Ahead

In September 2007, AMD at last unveiled its latest Barcelona processors for the Opteron line featuring what AMD touts as a native quad-core design. Some of the benefits from the new processors include greater power efficiency (maximum TDP of 68 - 95W) from independent clock domains and power management for each core and internal core and cache enhancements like HyperTransport 3.0. However, AMD's initial Opterons were at a modest 2GHz compared with 3GHz processors from Intel. Even clock for clock, the Barcelona Opterons were not that competitive against its Intel counterparts in terms of both performance and power efficiency. It had obvious improvements from the previous micro-architecture but they looked inadequate against Intel's Core 2.

The desktop K10 variants, the Phenom were to follow the Opterons in November 2007. Dubbed the Phenom X4 for its quad-cores, these desktop processors hit a snag in the form of a TLB (translation lookaside buffer) bug shortly after its launch. This was quickly fixed via a BIOS update that unfortunately also had a performance penalty side effect. AMD had to go back to the factory and months later in March 2008, released a new B3 stepping of the Phenom that solved the issue. However, time waits for no man and certainly not for AMD. By then however, Intel's 45nm Wolfdale and Yorkfield processors were already available in the market and their process technology edge meant that in power efficiency, Intel only extended its lead while in performance benchmarks, the Phenom X4 found itself facing higher clock dual-core rivals in the same segment.

New Forays and What's to Come

2008 also saw Intel going back to its roots in a big way, with a new line of low power processors known as the Atom that takes its architectural inspiration from Intel's older Pentium micro-architecture. Emphasizing a low TDP rating of 4W and less, the Atom has helped fuel a growing interest in portable low-power computing devices and the entry of the chip giant has seen a chorus of new products utilizing the Atom processor. Possible competitors have already sprung up in the form of NVIDIA's Tegra and VIA's Isaiah and it's still too early to tell if Intel will come to dominate this segment too.

As we approach the last quarter of 2008, AMD is working towards its own 45nm process shrink for its K10 processors, with plans for dual-core versions of its Phenom processors to follow its triple-core Phenom launched in April. Intel meanwhile is going full steam on its next generation Nehalem micro-architecture which is to succeed the Core and expected to be released later this year and in 2009. With up to 8 processing cores and a new integrated memory controller supporting DDR3, Nehalem shows that the core count will remain the next frontier for the x86 platform for the near future. Whether that is sufficient to extend Moore's Law remains to be seen.

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