AMD Athlon 64 FX microprocessor family

Athlon 64 FX family was introduced at the same time as Athlon 64. While the Athlon 64 microprocessors were intended for desktop computer marker, the Athlon 64 FX was primarily aimed at PC enthusiasts willing to pay premium price for premium performance. FX microprocessors were and still are very expensive - the cost of FX processors was/is at least 50% higher than the price of fastest Athlon 64 or Athlon 64 X2 processor on the market at the time. Difference in performance between FX and fastest Athlon 64/64 X2 was/is about 5% - 15% depending on application, which is significantly smaller than the difference in price. Better performance of FX CPUs was primarily due to higher clocked core and in some cases bigger L2 cache. The microprocessors could have other features making them faster. For example, socket 940 Athlon 64 FX processors had dual-channel memory controller, as opposed to Athlon 64 having only single-channel memory controller.

Athlon 64 FX processors have two-digit model numbers. Single core FX processors have odd model numbers. Dual-core CPUs have even model numbers. Model numbers can be used to tell which FX CPU is faster (higher is faster), but, unlike model numbers of other Athlon and Sempron processors, FX's model numbers cannot be used to estimate how the CPU will perform in comparison with other AMD or Intel microprocessors.