The introduction of the AMD64 line of processors was a rousing success on many levels, but there were a few niggling issues to address. The Athlon 64 FX-51 940-pin represented the new high-end of the processor scale, featured a powerful dual-channel memory controller, and supported both 32 and 64-bit software, but it could only use registered DDR. This was a carryover from its Opteron roots, and resulted in consumers not only having to shell out more money for registered DDR, but also contending with non-standard DDR that could not be transitioned to other AMD or Intel desktop systems. AMD subsequently upgraded the line to the higher-clocked Athlon 64 FX-53, but the issue of registered DDR support remained.
The same could be said of the mainstream Athlon 64 754-pin line, and while these processors did support standard unbuffered DDR, it was only through a single-channel DDR controller. The Athlon 64 3400+ provided definite high-end performance and features, but was still no way to get the top-end AMD system using industry standard DDR. Add to that the inherent incompatibility between the two Socket designs, which caused upgrade concerns from potential buyers, and gave Intel and their Socket 478 the upper hand. AMD really needed to combine the two platforms into one enthusiast-level design, incorporating the best from the Socket 940 and Socket 754 camps.
The platform convergence has finally come in the form of Socket 939, and it does offer the best of both AMD64 worlds. The high-end features such as dual-channel DDR have remained intact, while memory support has moved to unbuffered DDR. The latest AMD64 processors now share a common platform, including both Athlon 64 FX and Athlon 64 models of varying speeds and model numbers. This signals a transition to Socket 939 for the high-end market, but Socket 754 will still be active for mainstream and value buyers looking to get on the AMD64 train. AMD still has two distinct platform lines, but Socket 939 is a huge step in the right direction.
Today AMD introduces four new processors, including the Athlon 64 FX-53, Athlon 64 3800+ and Athlon 64 3500+ 939-pin models, and a high-end Athlon 64 3700+ upgrade to the 754-pin line. In our review, we're concentrating on the enthusiast-level and we'll be taking the new 739-pin Athlon 64 FX-53 and Athlon 64 3800+ processors for a spin to see how they compare against the current AMD and Intel lines.
The Athlon 64 3800+ is a totally new core iteration, and basically takes a bit from the Athlon 64 and Athlon 64 FX lines. The core speed is the most noticeable change, and the Athlon 64 3800+ is clocked at 2.4 GHz, or on par with the Athlon 64 FX-53 and a full 200 MHz higher than the Athlon 64 3400+. The integrated memory controller has been upgraded to dual-channel DDR to match the Athlon 64 FX, and brings unbuffered PC3200 support to the performance crowd.
The internal architecture of the Athlon 64 3800+ is also different than other high-end AMD processors, and while it shares the 128K L1 cache of the Athlon 64, the new 939-pin models sport only 512K of L2 cache. This design is similar to the existing value Newcastle core models, such as the Athlon 64 3000+, which has the same 2.0 GHz clock speed at the Athlon 64 3200+ (1-MB of L2 cache). The drop in L2 cache size has also decreased the number of transistors and die size of the Athlon 64 3800+. The remaining specifications are unchanged, and the Athlon 64 3800+ is produced using a 0.13-micron process, runs at a 1.5V core voltage, and has similar thermal and power requirements.
The AMD model numbering system is also worth a closer look, as AMD has introduced the Athlon 64 3800+ 939-pin and 3700+ 754-pin models, both running at 2.4 GHz. The 100 point difference in the model numbers suggests AMD is factoring in the dual-channel DDR feature of the Athlon 64 3800+, giving it a model number advantage over the single-channel DDR Athlon 64 3700+. The wildcard is the different L2 cache levels between processors, as the Athlon 64 3700+ includes a full 1-MB of L2 cache, or double that of the Athlon 64 3800+. As always, the proof is in the pudding, and we'll be looking over the benchmarks to see how the new AMD model numbers stack up.
The Athlon 64 3800+ may have been a new core design, but the 939-pin Athlon 64 FX-53 is a basic port over to the unbuffered DDR camp. The new Athlon 64 FX-53 shares the exact same physical specifications as the original model, such as a 2.4 GHz clock speed, 128K L1/1-MB L2 cache levels, a 0.13-micron process, and an integrated dual-channel DDR controller. This release has its good and bad points, and while we would have loved to see a higher-clocked (Athlon 64 FX-55?) model to really kick off the Socket 939 party, it is nice to see AMD's top-end processor get the industry standard DDR treatment, and shuffling off its Opteron coils.
The 939-pin Athlon 64 FX-53 shares the same name as its 940-pin counterpart, and we don't really anticipate any earth-shattering performance gains. Then again, the move to unbuffered DDR will shore up memory performance and get rid of the added memory latencies of registered DDR. The presence of standard DDR should amount to a nominal performance gain for the 939-pin Athlon 64 FX-53, but it really isn't the main focus of the upcoming performance section. The Athlon 64 FX-53 vs. Athlon 64 3800+ bout is the real deal, as these two 2.4 GHz powerhouses are equivalent in every way but L2 cache size, and it will be very interesting to see how these stack up in real-world testing.