The Athlon 64 X2, based on the Windsor core, is the backbone of AMD's socket AM2 offerings. All processors include a dual channel DDR2-800 memory controller and all command set extensions up to SSE3. This was also the first product generation where AMD introduced energy-efficient models, which run at a lower processor voltage and hence have a lower thermal design power (TDP). Compared to the Sempron we described on the previous page, this processor has two processing cores with 512 kB or 1 MB of L2 cache per core and TDP ratings of 89 W (up to 6000 and 3.0 GHz) or 125 W (6000 and 6400 at 3.2 GHz).

We used a 2.4 GHz Athlon 64 X2 4600 processor with two 512 MB L2 caches. As there is no 90 nm processor that runs at a 2.3 GHz clock speed, we used the 2.4 GHz version (instead of using only 2.2 GHz). The 65 nm versions of the Athlon 64 X2 have similar performance ratings (3600 to 5400), but AMD adjusted the clock speeds due to slight performance differences when compared to the 90 nm Windsor cores. The 65 nm Brisbane is only available with 2x 512 kB L2 cache, while the fast Windsors all utilize 2x 1 MB second level cache. Hence you will see that many 65 nm Athlon 64 X2 processors come with odd clock speeds of 2.1, 2.3, 2.5 or 2.7 GHz, to make up for the performance impact of the smaller cache.

When idle, the Athlon 64 X2 4600 will reduce its core clock speed to 1.0 GHz.