The number of dual core processors may be increasing, but that does not mean desktop software will suddenly catch up overnight. The vast majority of mainstream games and applications are single threaded, and AMD knows that along with introducing the powerhouse Athlon 64 X2 4800+ dual core, the company also needs to keep an eye on its single core performance as well. This comes in the form of the latest enthusiast part from AMD, the powerful Athlon 64 FX-57. Due to its lineage and design, this new Athlon 64 FX processor represents the very fastest single threaded performance on the market, but it will likely give up some ground to the dual core models when multi-threading is brought into the mix.
The Athlon 64 FX-57 is the latest addition to AMD's high-end enthusiast line, and brings a bit of new and old to the table. The basic architecture remains unchanged, and the Athlon 64 FX-57 features 128K of L1 and a full 1-MB of L2 cache, an integrated 128-bit memory controller, and runs on a bi-directional 2 GHz HyperTransport link. It also supports AMD technologies like Cool'n'Quiet, Enhanced Virus Protection, and is fully AMD64 compliant. AMD is not reinventing the wheel here, and the 2.8 GHz Athlon 64 FX-57 maintains the gap between standard Athlon 64 processors by including double the cache of the Athlon 64 3800+ and runs a full 400 MHz faster than the Athlon 64 4000+.
The main upgrade has been to boost clock speeds to 2.8 GHz for the Athlon 64 FX-57. On the surface the 2.8 GHz clock speed represents a 200 MHz jump over the 2.6 GHz Athlon 64 FX-55, but this is also the first Athlon 64 FX-based part to debut at 90nm and feature the San Diego core revision from Day 1. The new 90nm SOI core does allow for more headroom in terms of clock speeds, as well as lowering potential thermal output and power draw requirements. Its max thermal rating is 104W, which is exactly the same as the 2.6 GHz Athlon 64 FX-55, while the core voltage has dropped from 1.5V for the FX-55 to 1.35-1.40V for the FX-57. The maximum processor current has also dropped from 80A for the Athlon 64 FX-55 to 74.9A for the Athlon 64 FX-57.
The new 90nm core is not just a die shrink but also includes features and enhancements such as SSE3 and a revamped onboard memory controller. The controller now includes support for DDR400 operation with all four DIMM sockets populated (previously, it would default for DDR333 with 4 x double-sided DDR) and the ability to run mismatched DIIMMs in dual channel mode. Base memory performance has also been upgraded through improved memory mapping and lower memory latencies, but this also puts a bit more pressure on the DDR to achieve lower timings.
All Athlon 64 processors have the ability to drop multipliers down, and thereby achieve some flexibility when overclocking. The Athlon 64 FX line takes this a step further and is fully unlocked, thus allowing multipliers to be adjusted both up and down. This allows serious overclocking strategies to be employed, as well as tailoring the eventual clock and system/PCIe/PCI bus speeds to your specific configuration. The Athlon 64 FX also brought with it a "There Can Only Be One!" marketing strategy, but in a bit of a switch, AMD will also not be retiring the Athlon 64 FX-55, and instead will allow two FX models to exist concurrently.
Since we're dealing with a new 90nm core and the processor itself is unlocked, it is almost a license to overclock. The natural first step would be a 15x multiplier and increasing the core voltage while maintaining the 200 MHz internal clock, and achieving a 3.0 GHz final CPU clock speed. The system booted up immediately at these settings, hit Windows XP without an issue, and after a few tests we started to get visions of 3.2 GHz or higher. Then we had a crash, then another, and then the dreaded BSDs started cropping up, and no matter what we tried, 3.0 GHz would not remain stable. An eventual high clock speed of 2.94 GHz was achieved (14 x 210 MHz), but even this was a bit disappointing for a processor marketed directly at enthusiasts.
