Athlon 64 Explained

Athlon 64
Produced-Start:From 2004 to present
Arch:MMX, SSE, SSE2, SSE3, SSSE3, x86-64, 3DNow!
Microarch:K8 Microarchitecture
Sock1:Socket 754, Socket 939, Socket 940, Socket AM2

The Athlon 64 is an eighth-generation, AMD64-architecture microprocessor produced by AMD, released on September 23, 2003.[1] It is the third processor to bear the name Athlon, and the immediate successor to the Athlon XP.[2] The second processor (after the Opteron) to implement AMD64 architecture and the first 64-bit processor targeted at the average consumer,[3] it was AMD's primary consumer microprocessor, and competes primarily with Intel's Pentium 4, especially the "Prescott" and "Cedar Mill" core revisions. It is AMD's first K8, eighth-generation processor core for desktop and mobile computers.[4] Despite being natively 64-bit, the AMD64 architecture is backward-compatible with 32-bit x86 instructions.[5] Athlon 64s have been produced for Socket 754, Socket 939, Socket 940, and Socket AM2.


The Athlon 64 was originally codenamed ClawHammer by AMD,[3] and was referred to as such internally and in press releases. The first Athlon 64 FX was based on the first Opteron core, SledgeHammer. Both cores, produced on a 130 nanometer process, were first introduced on September 23, 2003. The models first available were the FX-51, fitting Socket 940, and the 3200+, fitting Socket 754.[6] Like the Opteron, on which it was based, the Athlon FX-51 required buffered RAM, increasing the final cost of an upgrade.[7] The week of the Athlon 64's launch, Intel released the Pentium 4 Extreme Edition, a CPU designed to compete with the Athlon 64 FX.[8] The Extreme Edition was widely considered a marketing ploy to draw publicity away from AMD, and was quickly nicknamed among some circles the "Emergency Edition".[9] Despite a very strong demand for the chip, AMD experienced early manufacturing difficulties that made it difficult to deliver Athlon 64s in quantity. In the early months of the Athlon 64 lifespan, AMD could only produce one hundred thousand chips per month.[10] However, it was very competitive in terms of performance to the Pentium 4, with magazine PC World calling it the "fastest yet".[11] "Newcastle" was released soon after ClawHammer, with half the Level 2 cache.[12]

All of the 64-bit processors sold by AMD so far have their genesis in the K8 or Hammer project.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

See 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]


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.


There are four variants: Athlon 64, Athlon 64 FX, Mobile Athlon 64 (later renamed "Turion 64") and the dual-core Athlon 64 X2.[39] Common among the Athlon 64 line are a variety of instruction sets including MMX, 3DNow!, SSE, SSE2, and SSE3.[40] All Athlon 64s also support the NX bit, a security feature named "Enhanced Virus Protection" by AMD.[41] And as implementations of the AMD64 architecture, all Athlon 64 variants are able to run 16 bit, 32 bit x86, and AMD64 code, through two different modes the processor can run in: "Legacy mode" and "long mode". Legacy mode runs 16-bit and 32-bit programs natively, and long mode runs 64-bit programs natively, but also allows for 32-bit programs running inside a 64-bit operating system.[42] All Athlon 64 processors feature 128 Kilobytes of level 1 cache, and at least 512 KB of level 2 cache.[40]

The Athlon 64 features an on-die memory controller,[5] a feature not previously seen on x86 CPUs. Not only does this mean the controller runs at the same clock rate as the CPU itself, it also means the electrical signals have a shorter physical distance to travel compared to the old northbridge interfaces.[43] The result is a significant reduction in latency (response time) for access requests to main memory.[44] The lower latency is often cited as one of the advantages of the Athlon 64's architecture over those of its competitors.[45]

Translation Lookaside Buffers (TLBs) have also been enlarged (40 4k/2M/4M entries in L1 cache, 512 4k entries),[46] with reduced latencies and improved branch prediction, with four times the number of bimodal counters in the global history counter.[42] This and other architectural enhancements, especially as regards SSE implementation, improve instruction per cycle (IPC) performance over the previous Athlon XP generation.[42] To make this easier for consumers to understand, AMD has chosen to market the Athlon 64 using a PR (Performance Rating) system, where the numbers roughly map to Pentium 4 performance equivalents, rather than actual clock speed.[47]

Athlon 64 also features CPU speed throttling technology branded Cool'n'Quiet, a feature similar to Intel's SpeedStep that can throttle the processor's clock speed back to facilitate lower power consumption and heat production.[48] When the user is running undemanding applications and the load on the processor is light, the processor's clock speed and voltage are reduced. This in turn reduces its peak power consumption (max TDP set at 89 W by AMD) to as low as 32 W (stepping C0, clock speed reduced to 800 MHz) or 22W (stepping CG, clock speed reduced to 1 GHz). The Athlon 64 also has an Integrated Heat Spreader (IHS) which prevents the CPU die from accidentally being damaged when mounting and unmounting cooling solutions. With prior AMD CPUs a CPU shim could be used by people worried about damaging the die.

The No Execute bit (NX bit) supported by Windows Vista, Windows XP Service Pack 2,[49] Windows XP Professional x64 Edition, Windows Server 2003 x64 Edition, and Linux 2.6.8 and higher is also included, for improved protection from malicious buffer overflow security threats. Hardware-set permission levels make it much more difficult for malicious code to take control of the system. It is intended to make 64-bit computing a more secure environment.

The Athlon 64 CPUs have been produced with 130 nm and 90 nm SOI process technologies.[50] All of the latest chips (Winchester, Venice and San Diego models) are on 90 nm. The Venice and San Diego models also incorporate dual stress liner technology[51] (an amalgam of strained silicon and 'squeezed silicon', the latter of which is not actually a technology) co-developed with IBM.[52]

As the memory controller is integrated onto the CPU die, there is no FSB for the system memory to base its speed upon.[53] Instead, system memory speed is obtained by using the following formula (using the ceiling function):[54]



In simpler terms, the memory is always running at a set fraction of the CPU speed, with the divisor being a whole number. A 'FSB' figure is still used to determine the CPU speed, but the RAM speed is no longer directly related to this 'FSB' figure (known otherwise as the LDT).

To summarize, the Athlon 64 architecture features two buses from the CPU. One is the HT bus to the northbridge connecting the CPU to the chipset and device attachment bus (PCIe, AGP, PCI) and the other is the memory bus which connects the on-board memory controller to the bank of either DDR or DDR2 DRAM.

Athlon 64 FX

The Athlon 64 FX is positioned as a hardware enthusiast product, marketed by AMD especially toward gamers.[55] Unlike the standard Athlon 64, all of the Athlon 64 FX processors have their multipliers completely unlocked.[56] The FX line is now dual-core, starting with the FX-60.[57] The FX always has the highest clock speed of all Athlons at its release.[58] From FX-70 onwards, the line of processors will also support dual-processor setup with NUMA, named AMD Quad FX platform.

Athlon 64 X2

See main article: Athlon 64 X2. The Athlon 64 X2 is the first dual-core desktop CPU manufactured by AMD.In 2007, AMD released two final Athlon 64 X2 versions: the AMD Athlon 64 X2 6400+ and 5000+ Black Editions. Both processors feature an unlocked multiplier, which allows for a large range of overclocked settings. The 6400+ is based on a 90nm Windsor core (3.2GHz, 2x1MB L2, 125W TDP) while the 5000+ is based on a 65nm Brisbane core (2.6GHz, 2x512KB L2, 65W TDP). These Black Edition processors are available at retail, but AMD does not include heatsinks in the retail package.

Turion 64 (formerly Mobile Athlon 64)

See main article: Turion 64. Previously introduced as "Mobile Athlon 64", Turion 64 is now the brand name AMD applies to its 64-bit low-power consumption (mobile) processors. The Turion 64 and Turion 64 X2 processors compete with Intel's mobile processors, initially the Pentium M and currently the Intel Core and Intel Core 2 processors.

Earlier Turion 64 processors are compatible with AMD's Socket 754. The newer "Richmond" models are designed for AMD's Socket S1. They are equipped with 512 or 1024 KB of L2 cache, a 64-bit single channel on-die memory controller, and an 800 MHz HyperTransport bus. Battery saving features, like PowerNow!, are central to the marketing and usefulness of these CPUs.

Model naming methodology

The model naming scheme does not make it obvious how to compare one Turion with another, or even an Athlon 64. The model name is two letters, a dash, and a two digit number (for example, ML-34). The two letters together designate a processor class, while the number represents a PR rating. The first letter is M for single core processors and T for dual core Turion 64 X2 processors. The later in the alphabet that the second letter appears, the more the model has been designed for mobility (frugal power consumption). Take for instance, an MT-30 and an ML-34. Since the T in the MT-30 is later in the alphabet than the L in ML-34, the MT-30 consumes less power than the ML-34. But since 34 is greater than 30, the ML-34 is faster than the MT-30.

Athlon Neo

With 27 mm × 27 mm in size and 2.5 mm in thickness, the Athlon Neo processors utilize a new package called "ASB1", essentially a BGA package, for smaller footprint to allow smaller designs for notebooks and lowering the cost. The clock of the processors are signficantly lower than desktop and other mobile counterparts to reach a low TDP, at 15W maximum for a single core x86 CPU. The Athlon Neo processors are equipped with 512 KB of L2 cache and HyperTransport 1.0 running at 800 MHz frequency.


At the introduction of Athlon 64 in September 2003, only Socket 754 and Socket 940 (Opteron) were ready and available. The onboard memory controller was not capable of running unbuffered (non-registered) memory in dual-channel mode at the time of release; as a stopgap measure, they introduced the Athlon 64 on Socket 754, and brought out a non-multiprocessor version of the Opteron called the Athlon 64 FX, as a multiplier unlocked enthusiast part for Socket 940, comparable to Intel's Pentium 4 Extreme Edition for the high end market.

In June 2004, AMD released Socket 939 as the mainstream Athlon 64 with dual-channel memory interface, leaving Socket 940 solely for the server market (Opterons), and relegating Socket 754 as a value/budget line, for Semprons and slower versions of the Athlon 64. Eventually Socket 754 replaced Socket A for Semprons.

In May 2006, AMD released Socket AM2, which provided support for the DDR2 memory interface. Also, this marked the release of AMD-V.

In August 2006, AMD released Socket F for Opteron server CPU which uses the LGA chip form factor.

In November 2006, AMD released a specialized version of Socket F, called 1207 FX, for dual-socket, dual-core Athlon FX processors on the Quad FX platform. While Socket F Opterons already allowed for four processor cores, Quad FX allowed unbuffered RAM and expanded CPU/chipset configuration in the BIOS. Consequentially, Socket F and F 1207 FX are incompatible and require different processors, chipsets, and motherboards.

Athlon 64 FX models

Sledgehammer (130 nm SOI)

Clawhammer (130 nm SOI)

San Diego (90 nm SOI)

Toledo (90 nm SOI)

Dual-core CPU

Windsor (90 nm SOI)

Dual-core CPU

Windsor (90 nm SOI) - Quad FX platform

See main article: AMD Quad FX platform. Dual-core, dual CPUs (four cores total)

Athlon 64 models

Clawhammer (130 nm SOI)

Newcastle (130 nm SOI)

Also possible: ClawHammer-512 (Clawhammer with partially disabled L2-Cache)

Winchester (90 nm SOI)

Venice (90 nm SOI)

San Diego (90 nm SOI)

Orleans (90 nm SOI)

Lima (65 nm SOI)

Athlon Neo

Huron (65 nm SOI)


See main article: AMD K10.

The Athlon 64 line is expected to continue to evolve. In particular, new models scheduled to be launched starting from the third quarter of 2007 are to be based on the "K10" microarchitecture. The initial offerings are expected to be based on the Agena (quad-core, 2 MB L3 cache), and Kuma (dual-core, 2 MB L3 cache) cores. These processors will be packaged in Socket AM2+ form factors, but are expected to function in Socket AM2 motherboards as well, with the loss of HyperTransport 3.0 enhancements, which will only be available with Socket AM2+ motherboards.

See also

External links

Notes and References

  1. Web site: AMD Ushers in Era of Cinematic Computing with the AMD Athlon 64 FX Processor. 2006-07-04. 2003-09-23.
  2. Web site: AMD's Athlon 64 Processor. 2006-07-07. 2003-09-23. Wasson. Scott.
  3. Web site: AMD Announces “AMD Athlon 64” As Brand Name For Next-Generation Desktop And Mobile Processors. 2006-07-04. 2002-11-19.
  4. Web site: - AMD K8 Architecture. 2006-07-04. 2004-02-18.
  5. Web site: Key Architecture Features. 2006-07-04.
  6. Web site: AMD's Athlon steps up to 64 bits. 2006-07-06. 2003-09-23. Spooner. John. CNET.
  7. Web site: AMD Athlon 64 & FX CPU processor. 2006-07-06.
  8. Web site: Intel Pentium 4 3.2 GHz Extreme Edition Processor Review. 2006-07-08. 2003-11-07. Angelini. C..
  9. Web site: Athlon 64, Athlon 64 FX and Pentium 4 Extreme Edition. 2006-07-06. 2003-09-23. De Gelas. Johan.
  10. Web site: AMD Athlon 64: Strong Demand or Weak Supply?. 2006-07-06. 2003-09-22. Shilov. Anton.
  11. Web site: First Tests of Athlon 64 PCs: Fastest Yet. 2006-07-07. 2003-09-23. Mainelli. Tom.
  12. Web site: AMD's Athlon 64 3400+: Death of the FX-51. 2006-07-06. 2004-01-06. Lal Shimpi. Anand.
  13. Web site: Socket 940 vs. 939. 2006-07-07. 2004-06-27.
  14. Web site: Meeting First Socket 939 Processors: AMD Athlon 64 3800+ and Athlon 64 3500+. 2006-07-07. Gavrichenkov. Ilya. 2004-06-01.
  15. Web site: AMD's Socket 939 Offers More with Much of the Same. 2006-07-06. 2004-06-01. Schmid. Patrick. Bert Töpelt.
  16. Web site: AMD Raises the Bar: AMD Athlon 64 FX-55 and AMD Athlon 64 4000+ CPUs Review. 2006-07-06. 2004-10-18. Gavrichenkov. Ilya.
  17. Web site: AMD Athlon 64 3800+ CPU: E3 Processor Core aka Venice at the Door. 2006-07-07. 2005-04-03. Gavrichenkov. Ilya.
  18. Web site: AMD64 3700+ San Diego S939 2.2 GHz. 2006-07-07. 2005-09-21. King. Greg.
  19. Web site: Microprocessor Types and Specifications. 2006-07-07. 2006-06-12.
  20. Web site: AMD's Athlon 64 3800+ "Venice" processor. 2006-07-07. 2005-05-17. Wasson. Scott.
  21. Web site: Enter Prescott: What's different about Intel's latest Pentium 4 variant?. 2006-07-07. 2004-07-01.
  22. Web site: AMD Athlon 64 Processors on E Core: Memory Controller Peculiarities in Detail. 2006-07-07. 2005-07-28. Gavrichenkov. Ilya.
  23. Web site: AMD Announces World’s First 64-Bit, x86 Multi-Core Processors For Servers And Workstations At Second-Anniversary Celebration Of AMD Opteron Processor. 2006-07-07. 2005-04-21.
  24. Web site: AMD “Shatters The Hourglass” With The Arrival Of The AMD Athlon 64 X2 Dual-Core Processor. 2006-07-07. 2005-05-31.
  25. Web site: Affordable Dual Core from AMD: Athlon 64 X2 3800+. 2006-07-07. 2005-08-01. Lal Shimpi. Anand.
  26. Web site: Athlon 64 X2 4600+ & 4200+ Processor Review. 2006-07-07. 2005-11-18. Freeman. Vince.
  27. Web site: CNET Prizefight: AMD vs. Intel dual-core CPUs. 2006-07-07. 2005-11-23. Brown. Rich.
  28. Web site: AMD's Dual Core Athlon 64 X2 Strikes Hard. 2006-07-07. 2005-05-09. Schmid. Patrick.
  29. Web site: AMD Introduces The AMD Athlon 64 X2 Dual-Core Processor 3800+. 2006-07-07. 2005-08-02.
  30. Web site: AMD Athlon 64 X2 Preview. 2006-07-07. Bennett. Kyle. 2005-05-09.
  31. Web site: AMD Desktop Processor Positioning. 2006-07-07.
  32. Web site: AMD Athlon 64 Rev F Update: DDR2 and Socket M2?. 2006-07-07. 2005-04-26. Shrout. Ryan.
  33. Web site: AMD Rejects DDR2, Gives Additional Speed Headroom for DDR. 2006-07-07. 2004-03-26. Shilov. Anton.
  34. Web site: AMD Delivers Desktop Product Powerhouse While Reducing Costs For Ecosystem Partners. 2006-07-07. 2006-05-23.
  35. Web site: Debut of AMD AM2: the long-awaited DDR2 on AMD Athlon X2. 2006-07-07. 2006-05-23. Romanchenko. Vladimir. Sofronov, Dmitry.
  36. Web site: AMD's AM2 Platform: Athlon 64 FX-62 Processor Review. 2006-07-07. 2006-05-23. Shrout. Ryan.
  37. Web site: AMD Socket AM2 Review. 2006-07-07. 2006-05-23.
  38. Web site: OCZ product page.
  39. Web site: AMD Athlon 64 Processor Family. 2006-07-04.
  40. Web site: AMD Athlon 64 Product Data Sheet. 2006-07-08. June. 2004. PDF.
  41. News: 'No Execute' Flag Waves Off Buffer Attacks. Breeden II. John. The Washington Post. 2005-02-27. 2006-07-08. F07.
  42. Web site: The Athlon 64 FX-51 Processor. 2006-07-08. 2003-09-23.
  43. Web site: AMD Athlon64 3200+ 32/64-bit Processor Review. 2006-07-07.
  44. Web site: Athlon 64 Venice 3800+ Review. 2006-07-07. Tong. Terren. 2005-05-03.
  45. Web site: Athlon 64 Vs. Pentium 4. 2006-07-04.
  46. Web site: A Glance at the Future: AMD Hammer Processors and x86-64 Technology. 2006-07-08. 2002-08-14.
  47. Web site: AMD Athlon XP/MP, Sempron and Athlon 64 model numbers. 2006-07-08.
  48. Web site: Cool'n'Quiet Technology Overview. 2006-07-08.
  49. Web site: CPU-Based Security: The NX Bit. 2006-07-04. 2004-05-24. Grevstad. Eric.
  50. Web site: AMD 90 nm power consumption measured. 2006-09-20. Wasson. Scott. 2004-10-04.
  51. Web site: AMD Athlon 64 3800+ CPU: E3 Processor Core aka Venice at the Door. 2006-09-20. 2005-04-03. Gavrichenkov. Ilya.
  52. Web site: AMD, IBM Dual Stress Liner Semiconductor Manufacturing Breakthrough. 2006-09-20. 2004-12-13.
  53. Web site: Front Side Bus. 2006-09-20. 2006-09-09.
  54. PC Magazine
  55. Web site: AMD Athlon 64 FX Processor Product Brief. 2006-07-04.
  56. Web site: AMD Athlon 64 FX-60 Review. 2006-07-08. 2006-07-05. Leeth. Tim.
  57. Web site: AMD Athlon 64 FX-60: A Dual-Core farewell to Socket-939. 2006-07-08. 2006-01-09. Lal Shimpi. Anand.
  58. Web site: AMD Athlon FX-60's Dual-Core Assault. 2006-07-08. 2006-01-10. Schmid. Patrick. Töpelt, Bert.
  59. Web site: DialyTech report: AMD Opteron 2200-series Works in Quad FX Motherboards.