Phenom: Barcelona For The Desktop

The successor to AMD’s Athlon desktop product line has been officially named: Phenom.


Developed under the codename Agena, the Phenom line is based on the same technologies being incorporated into the heavily-hyped Barcelona chips for servers. Like Barcelona, it will support the AM2 socket, so existing motherboards can use the new chip with just a BIOS  upgrade. It will come in dual and quad core flavors with the same integrated L3 cache as Barcelona and the 128-bit floating point unit.

There will be three Phenom product lines, the Phenom FX, X2 and X4, with X2 and X4 representing dual and quad core processors, respectively. AMD will keep the Athlon X2 and low-end Sempron but the single core Athlon and high-end Athlon FX will be replaced by Phenoms.

On the very high end, the FX will use Dual Socket Direct Connect, or DSDC. This effectively turns a dual processor machine, with four cores per processor, into an eight-core computer.

Other details are sketchy. It will be manufactured using a 65nm process but AMD  declined to comment on clock speed or power draw. David Schwarzbach, division market manager for the Desktop group at AMD, said it was difficult to come up with performance comparisons at this point, especially dual core vs. quad.

The expectation in dual-core to dual-core is around a 12 to 15 percent performance improvement, while quad-core is hard to say. “A development effort is needed to measure quad-core performance. Will it be double? I don’t think so. But it will be measurable,” he told

A 12 to 15 percent improvement struck In-Stat senior analyst Jim McGregor as rather underwhelming. “That’s kinda scary because they’re already trailing Intel,” he told “It’s not clear how that’s going to compare to Intel processors. Intel in the same time frame will have Penryn. It’s not clear at this point if they will even catch Intel in terms of performance and power efficiency, but they haven’t given us enough info to evaluate that.”

Just as AMD has promoted Barcelona’s native on-processor memory controller and native quad core design, Schwarzbach felt those two design differences would help it differentiate itself and compete with Intel’s offerings.

“Everything has to go through the front-side bus and their memory controller has its own clock speed, while the Phenom memory controller clocks at the frequency of CPU,” he said. “The front-side bus has its own clock speed which they can’t ramp. No doubt their product is more competitive than it’s been in years but they are doing it in a brute force, kludgy manner.”

Pricing has not been set, and AMD plans to release Phenom in the second half of this year. More details are expected to be released at the huge Computex show in Taipei, Taiwan in the first week of June.

McGregor said the Athlon architecture is still competitive, but the Agena/Barcelona changes are not big jumps. “You have to think that what they’re doing on this processor is enhancements, it’s not really a new microarchitecture,” he said.

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