The processor or CPU (Central Processing Unit) is the brains of the computer and is where most calculations take place. In terms of computing power, the CPU is the most important element of the computer.

CPUs come in different strengths.

The Athlon 64 X2 is the first dual-core desktop CPU designed by AMD. It is essentially a processor consisting of two Athlon 64 cores joined together on one die with additional control logic. The cores share one dual-channel memory controller, are based on the E-stepping model of Athlon 64 and, depending on the model, have either 512 or 1024 KB of L2 Cache per core. The Athlon 64 X2 is capable of decoding SSE3 instructions (except those few specific to Intel's architecture), so it can run and benefit from software optimizations that were previously only supported by Intel chips. This enhancement is not unique to the X2, and is also available in the Venice and San Diego single core Athlon 64s. In June 2007, AMD released low-voltage variants of their low-end 65 nm Athlon 64 X2, named "Athlon X2".[1] The Athlon X2 processors feature reduced TDP of 45 W.

Core 2 is a brand encompassing a range of Intel's consumer 64-bit x86-64 single-, dual-, and quad-core CPUs based on the Intel Core microarchitecture. The single- and dual-core models are single-die, whereas the quad-core models comprise two dies, each containing two cores, packaged in a multi-chip module.[1] The introduction of Core 2 relegated the Pentium brand to the mid-range market, and reunified laptop and desktop CPU lines, which previously had been divided into the Pentium 4, Pentium D, and Pentium M brands. The Core microarchitecture returned to lower clock rates and improved the usage of both available clock cycles and power when compared with the preceding NetBurst microarchitectue of the Pentium 4/D-branded CPUs.[2] The Core microarchitecture provides more efficient decoding stages, execution units, caches, and buses, reducing the power consumption of Core 2-branded CPUs while increasing their processing capacity. Intel's CPUs have varied wildly in power consumption according to clock rate, architecture, and semiconductor process, shown in the CPU power dissipation tables. Core-based processors do not have Hyper-Threading Technology found in Pentium 4 processors. This is because the Core microarchitecture is a descendant of the P6 microarchitecture used by Pentium Pro, Pentium II, Pentium III, and Pentium M. Core 2 also lacks an L3 Cache found in the Gallatin core of the Pentium 4 Extreme Edition, although an L3 Cache is present in high-end versions of Core-based Xeons and Hyper-Threading is present on select Atom processors. Both an L3 cache and Hyper-threading is present in current Nehalem and future Westmere processors. The Core 2 brand was introduced on July 27, 2006,[3] comprising the Solo (single-core), Duo (dual-core), Quad (quad-core), and in 2007, the Extreme (dual- or quad-core CPUs for enthusiasts) version.[4] Intel Core 2 processors with vPro technology (designed for businesses) include the dual-core and quad-core branches.