The Core 2 brand refers to a range of Intel's consumer dual-core and quad-core (2x2) 64-bit x86 CPUs based on the Intel Core microarchitecture, which derived from the 32-bit dual-core Yonah laptop processor. (Note: The Yonah comprised two interconnected cores — from the Pentium M branded microprocessor — coupled as a single die silicon chip or IC.) The 2x2 "quad-core" (dual-die dual-core[1]) comprised two separate dual-core dies next to each other in one CPU package. The Core 2 relegated the Pentium brand to a lower-end market, and reunified the laptop and desktop CPU lines separated by the Pentium M and Pentium 4 brands.
The Core 2 brand was introduced on July 27, 2006[2] comprising up to 2007[3] the Duo (dual-core), Quad (quad-core), and Extreme (dual- or quad-core CPUs for enthusiasts) branches. The Core 2 branded CPUs include: "Conroe" and "Allendale" (dual-core for higher- and lower-end desktops), "Merom" (dual-core for laptops), "Kentsfield" (quad-core for desktops), and their variants named "Penryn" (dual-core for laptops), "Wolfdale" (dual-core for desktops) and "Yorkfield" (quad-core for desktops). (Note: For the "Woodcrest", "Clovertown", and "Tigerton" CPUs for servers and workstations see the Xeon brand[4].
Unlike the preceding NetBurst architecture of the Pentium 4 or Pentium D branded CPUs, the Core architecture returned to lower clock speeds, and improved processor's usage of both available clock cycles and power. That translated into more efficient decoding stages, execution units, caches, and buses, etc, reducing the Core 2 CPU's power consumption, while enhancing their processing capacity. With a Thermal Design Power (TDP) of up to only 65 W, the Core 2 dual-core Conroe consumed only half the power of less capable, but also dual-core Pentium D branded desktop chips[5] with a TDP of up to 130 W[6] (a high TDP requires additional cooling that can be noisy or expensive).
Intel Core 2 processors feature the 64-bit x86-64 instruction set, Virtualization Technology (except T5500 or lower end E4x00), Execute Disable Bit, and SSE3. Core 2 also introduced SSSE3, Trusted Execution Technology, Enhanced SpeedStep, and Active Management Technology (iAMT2).
Typically for CPUs, the Core 2 Duo E4000/E6000, Core 2 Quad Q6600, Core 2 Extreme dual-core X6800, and quad-core QX6700 and QX6800 CPUs were affected by bugs, but apparently minor