A quad-core CPU has four processing cores in a single chip. It is very similar to a dual-core CPU, but it has four separate processors (in place of two), which process instructions at the same time.
Quad-core CPUs have become much more popular in the last few years when the clock speeds of these processors have increased significantly. Include multiple cores in a single CPU , but chip manufacturers can generate higher performance without boosting the clock speed. Performance gains can only be realized if the computer’s software supports multiprocessing. They allow the software to split the processing load between multiple processors (or “cores”), rather than using one processor at a time. The good thing is that most modern operating systems and many programs provide support for multiprocessing.
Some examples of quad-core CPUs are Intel Core 2 Quad, Intel Nehalem, and AMD Phenom X4 processors. These Intel processors are used in Mac, Windows, and Linux systems, while AMD processors are used only in Windows and Linux systems. Although these four cores look quite impressive, but some high end computers also use two quad-core CPUs, which provide a total of eight processing cores. Which is really much more core power!