Athlon 64 FX is a processor targeted to high-end gamers. Originally the difference between Athlon 64 and Athlon 64 FX was the amount of L2 memory cache (512 KB on Athlon 64 vs. 1 MB on Athlon 64 FX) and better overclocking capability, provided by an unlocked clock multiplier. All other CPUs from both Intel and AMD have a fixed clock multiplier, not allowing you to increase it – on all other CPUs the only way to overclock the CPU is to increase their external clock. Thus on Athlon 64 FX you have two options when overclocking the CPU: increasing the CPU base clock (also known as HTT clock), which defaults to 200 MHz, and/or increasing its clock multiplier.

When Athlon 64 processors started to be shipped also with 1 MB, the difference between them became the unlocked clock multiplier – Athlon 64 4000+ and Athlon 64 FX-53 are the same processor, for instance. Traditionally Athlon 64 CPUs with the highest clock rates are first released as Athlon 64 FX models.

Athlon 64 FX main features include:

• 64 KB instruction L1 memory cache and 64 KB data L1 memory cache per core.
• 1 MB L2 memory cache.
• HyperTransport bus running at 800 MHz (3.2 GB/s) or 1 GHz (4 GB/s). These clocks may also be referred as ”1,600 MHz“ or ”2,000 MHz“, respectively.
• DDR dual channel configuration on all models (you need to install two or an even number of memory modules to use this feature).
• Early Athlon 64 FX models used socket 940, which required ECC memory modules.
• SSE3 instruction set on some models.
• Dual-core feature on models ending with an even number (FX-60 is the first dual-core Athlon 64 FX). Dual-core processors have two complete CPUs inside. Read our tutorial Dual Core AMD Processors to learn more about this technology.
• Socket AM2 and socket F models work with DDR2 memories, while socket 939 and 940 work with DDR memories.

In the table below we list all Athlon 64 FX released to date. TDP means Thermal Design Power and indicates the thermal dissipation of the CPU, i.e., the CPU cooler must be capable of dissipating at least this amount of heat.