On June 1, 2004, AMD released new versions of both the ClawHammer and Newcastle core revisions for the newly-introduced Socket 939, an altered Socket 940 without the need for buffered memory.[13] Socket 939 offered two main improvements over Socket 754: the memory controller was altered with dual-channel architecture,[14] doubling peak memory bandwidth, and the HyperTransport bus was increased in speed from 800 MHz to 1000 MHz.[15] Socket 939 also was introduced in the FX series in the form of the FX-55.[16] At the same time, AMD also began to ship the "Winchester" core, based on a 90 nanometer process.

Core revisions "Venice" and "San Diego" succeeded all previous revisions on April 15, 2005. Venice, the lower-end part, was produced for both Sockets 754 and 939, and included 512 KB of L2 cache.[17] San Diego, the higher-end chip, was produced only for Socket 939 and doubled Venice's L2 cache to one MB.[18] Both were produced on the 90 nm fabrication process.[19] Both also included support for the SSE3 instruction set,[20] a new feature that had been included in the rival Pentium 4 since the release of the Prescott core in February 2004.[21] In addition, AMD overhauled the memory controller for this revision, resulting in performance improvements as well as support for newer DDR RAM.[22]

 Dual-core Athlon 64

Main article: Athlon 64 X2

On April 21, 2005, less than a week after the release of Venice and San Diego, AMD announced its next addition to the Athlon 64 line, the Athlon 64 X2.[23] Released on May 31, 2005,[24] it also initially had two different core revisions available to the public, Manchester and Toledo, the only appreciable difference between them being the amount of L2 cache.[25] Both were released only for Socket 939.[26] A response to Intel's dual core Pentium D, the Athlon 64 X2 was received very well by reviewers and the general public, with a general consensus emerging that AMD's implementation of multi-core was superior to that of the Pentium D.[27][28] Some felt initially that the X2 would cause market confusion with regard to price points since the new processor was targeted at the same "enthusiast," US$350 and above market[29] already occupied by AMD's existing socket 939 Athlon 64s.[30] AMD's official breakdown of the chips placed the Athlon X2 aimed at a segment they called the "prosumer", along with digital media fans.[24] The Athlon 64 was targeted at the mainstream consumer, and the Athlon FX at gamers. The Sempron budget processor was targeted at value-conscious consumers.[31]

 DDR2

See also: AMD#Athlon 64 (K8)

The Athlon 64 had been maligned by some critics for some time because of its lack of support for DDR2 SDRAM, an emerging technology that had been adopted much earlier by Intel.[32] AMD's official position was that the CAS latency on DDR2 had not progressed to a point where it would be advantageous for the consumer to adopt it.[33] AMD finally remedied this gap with the "Orleans" core revision, the first Athlon 64 to fit Socket AM2, released on May 23, 2006.[34] "Windsor", an Athlon 64 X2 revision for Socket AM2, was released concurrently. Both Orleans and Windsor have either 512KB or 1MB of L2 cache per core.[35] The Athlon 64 FX-62 was also released concurrently on the Socket AM2 platform.[36] Socket AM2 also consumes less power than previous platforms, and supports AMD-V.[37]

The memory controller used in all DDR2 SDRAM capable processors (Socket AM2), has extended column address range of 11 columns instead of conventional 10 columns, and the support of 16 KB page size, with at most 2048 individual entries supported. An OCZ unbuffered DDR2 kit, optimized for 64-bit operating systems, was released to exploit the functionality provided by the memory controller in socket AM2 processors, allowing the memory controller to stay longer on the same page, thus benefitting graphics intensive applications.[38]

 Moving to the subnotebook space

The Athlon architecture was further extended with the release of Athlon Neo processors on January 9, 2009. Based on the same architecture as the other Athlon 64 variants, the new processor features a small package footprint targeting Ultra-portable notebook market.