This article originally appeared on Hardware Central.

Dual-core processing was definitely the hottest new technology of 2005, with twin-engine chips making amazing market gains throughout the second half of the year. Since last summer, when Intel introduced and AMD immediately followed with dual-core CPUs, both high-end enthusiast desktops and affordable family PCs have boarded the bandwagon. When you start seeing mom-and-pop computer stores advertising dual-core systems, you know a technology has officially arrived.

Dual-core represents the past, present, and near future of desktop processing, but the wheels of technology never stop spinning: Dual-core driver support is increasing, more multithreaded software is on the way, and even Apple has gotten into the act. So why should AMD and Intel stop at two cores, any more than Gillette and Schick stopped at two blades? If the CPU giants have their way, 2007 will be the year of quad-core processors.

The War Times Four

Intel has announced that it will start shipping quad-core processors as early as the fourth quarter of this year, but as usual the newest CPU technology will hit the server market first. There are still questions on whether Intel can make its deadline, but its first quad-core models (codenamed "Clovertown") will join the Xeon server/workstation line and compete against AMD's surprisingly strong Opteron. The latter has Intel definitely feeling the heat in terms of server market share, potentially doing more damage than AMD's Athlon 64 series can do in the desktop segment. Being first to ship quad-core could help Intel in both market- and mindshare.

On the desktop side, Intel's new "Conroe" architecture (replacing the Pentium family's NetBurst) is slated for a mid-2006 debut as a dual-core part. Intel won't bring quad-core design to the desktop until 2007, when the Clovertown-like "Kentsfield" will hit the high-end gaming and workstation markets. By then, Intel will have moved its desktop, mobile, and enterprise CPUs alike to the next-generation architecture, expected to require less power, produce lower heat, and cost less to produce than today's high-end Pentium D and Pentium Extreme Edition processors.

AMD's first move toward a quad-core product line will be to introduce the new AM2 processor socket and add support for DDR-2 memory. Just as Socket 939 created a one-size-fits-all solution for high-end AMD processors, so too will the AM2 socket be the building block for AMD's next-generation platforms. Throughout 2006, expect higher-clocked revisions of existing dual-core processors, including an Athlon 64 X2 5000+ and FX-62, along with a migration of existing CPUs to AM2 and DDR-2. Once 2007 rolls around, AMD plans to offer a drop-in quad-core solution for Opteron AM2 platforms, followed by a desktop version some time later.

The Quad-Core Laundry List

Naturally, incorporating four cores into one physical processor brings some design challenges. Today's dual-core models have higher power requirements and produce more heat than their single-core siblings, and doubling up on the difference just isn't in the cards. The most obvious solution is to shrink the die size, where Intel and AMD currently use 65-nanometer and 90-nanometer process technology, respectively. The next step is going to benefit AMD more than Intel, as the Athlon 64's 65nm transition is slated for later this year while it's doubtful Intel can move to 45nm in time. Current power and heat comparisons pit 90nm Athlon 64 X2 processors against the 65nm Pentium D, so AMD's gains in moving to 65nm should be immense, whereas Intel's 65nm dual-core NetBurst was mostly a wash.

Creating a whole new processor architecture or platform is another possible solution, and that's exactly what Intel will do in 2006, when Conroe and the mobile "Meron" will supposedly take the best from the Pentium M and Pentium 4 designs to create a new flagship hybrid. AMD's less radical move will be to the new AM2 socket design, which will start as the new home of the Opteron and then transition to Athlon 64 desktop models. The best part is that AMD's quad-core processors will also support AM2, similar to how the Athlon 64 X2 stuck with Socket 939. This type of longevity is a real draw for many buyers, and gives AMD an advantage compared to Intel, which seems to change platforms at least once or twice a year.

This socket discussion also leads into the need for faster CPU and system bus speeds, in order to accommodate four cores working in concert. Platform bottlenecks are a real issue in the dual-core world, and will only get worse as additional cores battle for finite system resources. This is noticeable with the current Pentium D running on Intel's 800MHz front-side bus, so the company is slated to release dual-core Conroe on the 1066MHz bus with some bandwidth enhancements.

AMD also has a few tricks up its sleeves, as a revised HyperTransport bus will accompany the AM2 socket, with the move to high-speed DDR-2 allowing additional memory bandwidth. Adding extra cache to the processor itself is another possible solution, and AMD is rumored to be doing just that by adding 4MB of Level 3 cache to upcoming Athlon 64 FX models.

A Change in the Air

Although the hardware is in place, there is still a lack of multithreaded software. That's the weakness of any new multiprocessing initiative, especially since only a portion of the installed base now has these capabilities, so the payoff is not high enough to warrant the extra coding work. A one-and-a-half-core technology like Hyper-Threading had potential, but only high-end Intel processors included it, and its partitioned single-core design meant the jump in multithreaded performance was not significant. Therefore, without a lucrative market or the potential for significant performance gains, developers sat on their hands and kept pumping out single-threaded apps and games.

True dual-core technology has changed the landscape significantly. Both AMD and Intel are moving ahead with dual-core processors as their mainstream solutions, with the former taking the extra step to convert its Athlon 64 FX line to dual-core. Intel may not offer the same level of performance, but the low-cost Pentium D 820 (2.8GHz) may have done more for dual-core popularity than any other factor.

The shift is almost palpable, with graphics-card vendors jumping over each other to release "dual-core enhanced" drivers while game developers add multithreaded patches to existing games and promise full support with upcoming titles. Enterprise server-style virtualization also gains ground, as running multiple operating systems becomes a much more viable solution with four cores pushing data.