AMD's dual-core CPUs come out fighting

Two weeks ago, AMD released its dual-core Opteron server chips and announced that we'd soon see dual-core technology brought to the desktop in the form of its Athlon 64 X2 processors. We have tested one of the new chips, and today we can share performance figures. The results are dramatic. AMD's new dual-core Athlon 64 X2 4800+ CPU hands the company a decisive victory over rival Intel; a system from AMD using the X2 4800+ beat an Intel-submitted PC with the Pentium Extreme Edition 840 (PEE 840) on every one of our dual-core benchmarks.

With four Athlon 64 X2 chips announced today, AMD gives PC buyers greater dual-core CPU choices than you get with Intel and its lone PEE 840. What's more, the Athlon 64 X2 chips work with existing AMD motherboards, providing DIY consumers flexibility in bringing dual core to their current platform without having to overhaul the entire PC, starting with the motherboard.

AMD's initial shipment will consist of four different CPUs. We received a test system from AMD with the highest-end Athlon 64 X2 4800+ ($1,001) chip. The X2 4600+ ($803), the X2 4400+ ($581) and the X2 4200+ ($537) round out the line. Both the X2 4800+ and the X2 4600+ are clocked at 2.4GHz; the X2 4800+ costs more because it has 1MB of L2 cache on each processing core to the X2 4600+ core's 512KB. The X2 4400+ and the X2 4200+ both have a clock speed of 2.2GHz, with a similar breakdown of L2 cache: 1MB on each X2 4400+ core and 512KB on each X2 4200+ core.

Sending the message
Although AMD has not released the names of the vendors that will sell systems with the Athlon 64 X2 processors, it has told us that the chips will first appear in digital-content-creation and general productivity PCs from four major desktop companies, followed by a wider release to the OEM market. By staying away from gaming systems, AMD plays to dual core's strengths better than Intel did on its initial release, which featured game-oriented systems such as Dell's Dimension XPS Gen 5. Although both the Intel PEE 840 and the Athlon 64 X2 will play games fast enough because of their high clock speeds, today's games can't take advantage of a dual-core CPU's ability to process multiple software strings simultaneously. Until a multithreaded game hits the market, the single-core AMD Athlon 64 FX-55 is still the CPU of choice for high-end gaming PCs.

Because AMD's processors use a different chipset than Intel's and the comparison 'white box' units use different memory, hard drives and other hardware, we can't make a perfect direct comparison between the two CPUs. The best we can do is set every component to factory specs and compare those baseline-to-baseline results. Using that methodology, we found AMD's chip the clear winner. Still, it's hard to pinpoint specifically why the Athlon 64 X2 4800+ is faster than the Pentium Extreme Edition 840. AMD claims its chip is lightning-fast because of its built-in memory controller -- and judging from our dual-core tests, we'd have to agree that it plays a part in giving AMD the edge. Intel's PEE 840 must communicate with system memory via a separate memory controller connected via the frontside bus (FSB), a pathway on which data can travel at 1,066MHz at best. With its integrated memory controller, the Athlon 64 X2, AMD's chip removes the FSB bottleneck and can communicate with system memory at the processor's full clock speed.

Dual-core CPUs are designed to run not only multiple applications at the same time better than single-core processors, but also multithreaded applications such as Apple iTunes and Adobe Photoshop. On our multitasking benchmark, which runs McAfee's VirusScan 2005 while encoding video with DivXNetwork's Dr.Divx, the AMD Athlon 64 X2 4800+ white box beat the 3.2GHz Intel Pentium Extreme Edition 840 white box by 10 percent. It's worth noting that the Velocity Micro ProMagix DCX beat the X2 4800+ system by 17 percent on the same test, but the ProMagix features a PEE 840 overclocked to 4.0GHz. Unlike Intel's chips, AMD has locked the clocks on the Athlon 64 XS series. But to get the PEE 840 to run that fast, Velocity Micro had to install a complicated liquid-cooling system to ensure that the processor wouldn't overheat. System-building hobbyists might appreciate the PEE 840's hidden multitasking potential, but for most users, the Athlon 64 X2 4800+ is the winner.

Our multithreaded application test showed an even more decisive victory for the AMD chip. Using Apple's iTunes to encode WAV files to MP3, not only did the Athlon 64 X2 4800+ system beat the Intel PEE 840 white box PC by 22 percent, but the X2 4800+ white box also edged the overclocked Velocity Micro ProMagix DCX by 3 percent. Statistically that difference is within our margin of error, making it a virtual tie. But the fact that the X2 4800+ is able to deadlock a chip running nearly twice as fast speaks very highly of AMD's architecture and the chip's overall superiority.

On the whole, when you remove overclocking from the equation and compare AMD's dual-core white box to Intel's, AMD is the clear winner at every turn. On all seven of our dual-core benchmarks, the Athlon 64 X2 4800+-based system returned a faster time, with an average performance gain of 15.2 percent across the board. The two systems were closest on the Cinebench 2003 test, where the AMD system was only 1.6 seconds (or 3.9 percent) faster than the Intel. The largest margin of victory was with our McAfee VirusScan test, where the AMD system completed the test in 130 seconds to the Intel system's score of 168 seconds (29.2 percent faster).

How does AMD's new dual-core Athlon 64 X2 processor stack up against Intel's Pentium Extreme Edition 840? We have some preliminary – and dramatic – benchmarks.