There are two main differences between Athlon 64 X2 and dual-core versions of Athlon 64 FX. First, they have different L2 cache sizes. While each Athlon 64 X2 core has a 512 KB L2 memory cache, each core of dual-core Athlon 64 FX has a 1 MB L2 memory cache. Another difference between them is the fact that Athlon 64 FX has its clock multiplier unlocked, i.e., you can increase its clock multiplier in order to achieve a higher clock rate.

Athlon 64 X2 4600+ runs at 2.4 GHz, the same clock rate as Athlon 64 3800+, multiplying its base clock of 200 MHz by 12. Athlon 64 FX-60 runs at 2.6 GHz, multiplying its base clock of 200 MHz by 13.

Figure 5: Athlon 64 X2 4600+ specs.

Figure 6: Athlon 64 FX-60 specs.

We didn’t compare these CPUs with Intel counterparts (namely Pentium D and Pentium Extreme Edition) because unfortunately Intel didn’t provide us samples for reviewing.