x2

The Athlon 64 X2 is the first native dual-core desktop central processing unit (CPU) designed by Advanced Micro Devices (AMD). It was designed from scratch as native dual-core by using an already multi-CPU enabled Athlon 64, joining it with another functional core on one die, and connecting both via a shared dual-channel memory controller/north bridge and additional control logic. The initial versions are based on the E stepping model of the Athlon 64 and, depending on the model, have either 512 or 1024 KB of L2 cache per core. The Athlon 64 X2 can decode instructions for Streaming SIMD Extensions 3 (SSE3), except those few specific to Intel's architecture. The first Athlon 64 X2 CPUs were released in May 2005, in the same month as Intel's first dual-core processor, the Pentium D.
In June 2007, AMD released low-voltage variants of their low-end 65 nm Athlon 64 X2, named "Athlon X2". The Athlon X2 processors feature reduced thermal design power (TDP) of 45 Watt (W). The name was also used for K10 based budget CPUs with two cores deactivated.

View More On Wikipedia.org