3.3 Processor

The processor (also called a CPU, or central processing unit) is at the core of a computer. Every bit of data must go through the CPU to be processed. In older mainframe computers, the CPU refers to a large desk-sized assembly. However, in most computers today, the CPU is usually a single integrated circuit (IC).

Many factors influence of the processing power of a CPU (or how quickly it can process data).

• Core frequency. This is the maximum frequency of the processor. The higher the frequency, the higher the processing power. However, this frequency by itself does not dictate the overall performance of a processor. By today’s (2008) standard, a fast processor has a core frequency of about 3GHz (3 billion cycles per second).
• Front side bus (FSB) frequency. The FSB frequency limits the number of data transfers that can occur between the CPU and the Northbridge on the motherboard. This frequency is not measured in Hertz (Hz), but rather “transfer per second”. Most modern CPUs have a FSB specification that exceeds 1,000MT/s (one thousand million transfers per second). A higher FSB frequency means a CPU can transfer data faster to all other components, resulting in better performance.
• Cache. Cache memory is a special type of memory that can keep up at the core frequency. It buffers the slow traffic to memory (which is restricted by the FSB frequency and memory speed). More cache memory means the processor core does not need to access memory as much, which results in better performance. By today’s standard, 3MB (3 million bytes) per core is a reasonable amount.
• Number of cores. Many modern CPUs have multiple processor cores on a single IC. A higher number of cores can potentially improve the performance of a system. However, the actual performance gain depends greatly on the type of application and operating system used.

A CPU IC emits a lot of heat. For example, an Intel Q6600 CPU has a maximum heat dissipation rating of 140W (140 watts). Combined with the realtive small size of a CPU, heat extracting (or heatsinking) becomes an important issue. There are many choices of CPU coolers, some work much better than others. A higher CPU temperature means the CPU can die sooner.