Socket 754 ? 939 ? 130nm and 90nm fabrication process? This test is for those who are lost in AMD’s line of products. Here is a comparative test of 16 processors including 12 Athlon 64s. The P-Rating is sometimes just the tip of the iceberg.
The Athlon 64-review
Before getting to the heart of the matter, a little bit of background on the Athlon 64 is necessary. Released in September, 2003, the Athlon 64 processors are based on AMD’s K8 architecture. The K7 architecture was introduced along with the first Athlon Slot A in 1999.
The K8 architecture is essentially based on K7 processing units. Still, AMD also brought several innovations to improve the overall performance of this new core:
- 130 nm SOI fabrication process
- Increased pipeline size
- Integration of a memory controller
- Integration of a HyperTransport controller
- Improvement of the cache L2
- Addition of SSE2 instructions
- Extension of the x86 to 64 bits
In practice, one of the most important changes was the integration of the memory controller, which until then was controlled by the chipset. This integration strongly reduced memory latency and increased overall performance. Other improvements were also significant and it’s important to take into account that one is still unactivated-the extension of the x86 set of instructions to 64 bits, only compatible with the “alternative” OS. The release of Windows XP x64 has been postponed from the second quarter of 2004 to the first half of 2005.
Compared to Intel’s Pentium 4 processors, the Athlon 64s are generally faster for games and scientific calculations and slower for 3D processing and video. Of course this judgment is based on several series of tests and may vary with applications. The purpose of this test isn’t to compare AMD’s processor to Intel’s, as we’ve already published several articles on this subject.
Several Athlon 64 versions
Several characteristics distinguish the current Athlon 64. The first is its use of the 757 or 939 Socket. This figure corresponds to the number of processor pins. Of course the additional 185 pins of the Athlon 64 Socket 939 aren’t just there for looks, but rather to control a second 64 bit DDR memory channel. If the Socket 754 controls memory on a single 64 bit channel, with 3.2 GB and some PC3200s, the Socket 939 controls memory on two 64 bit channels and with a cumulated bandwidth of 6.4 GB/s. In practice the performance gain varies from 0 to 7%.
The second characteristic is, of course, frequency or processor speed expressed in the number of cycles per second. It varies from 1800 Mhz to 2600 MHz depending on the model.
Cache size is also important. Initially all AMD processors were equipped with 1024 kb of cache L2 in addition to 128 Ko of cache L1. AMD, however, rapidly changed this configuration, and later they were equipped with 512 KB of cache L2, but with an increased frequency. Only high end products are now equipped with 1024 KB of cache L2. The performance gain varies from 0 to 5M (depending on the application) compared to a 512 KB processor with an equivalent frequency.
The third difference is the fabrication process of 130 or 90 nm. With an equivalent number of transistors, the smaller fabrication process makes it possible to reduce the die size and, in theory, electrical consumption. We verify this later in this article.
AMD currently offers no less than 12 processors with different combinations of these three characteristics:
- 2800+ S754 : 1800 MHz, 512 KB of L2, 1 channel DDR, 130nm
- 3000+ S754 : 2000 MHz, 512 KB of L2, 1 channel DDR, 130nm
- 3200+ S754 : 2200 MHz, 512 KB of L2, 1 channel DDR, 130nm
- 3400+ S754 : 2400 MHz, 512 KB of L2, 1 channel DDR, 130nm
- 3700+ S754 : 2400 MHz, 1024 KB of L2, 1 channel DDR, 130nm
- 3000+ S939 : 1800 MHz, 512 KB of L2, 2 channels DDR, 90nm
- 3200+ S939 : 2000 MHz, 512 KB of L2, 2 channels DDR, 90nm
- 3500+ S939 : 2200 MHz, 512 KB of L2, 2 channels DDR, 90nm
- 3500+ S939 : 2200 MHz, 512 KB of L2, 2 channels DDR, 130nm
- 3800+ S939 : 2400 MHz, 512 KB of L2, 2 channels DDR, 130nm
- 4000+ S939 : 2400 MHz, 1024 KB of L2, 2 channels DDR, 130nm
- FX-55 S939 : 2600 MHz, 1024 KB of L2, 2 channels DDR, 130nm
This list only includes 9 P-Ratings. A 3000+ whether a Socket 754 or a Socket 939 will be clocked at 2.0 or 1.8 Ghz. In the past, the P-Rating was even more complicated. It was possible to find a 3400+ clocked at 2.4 GHz with 512 KB of cache and another 2.2 GHz with 1024 KB of cache. Precedent tests showed that the former processor was, in fact, the most efficient. Cache size doesn’t compensate for the difference in frequency.
