Significance

• Nearly all marketing efforts for processors place an emphasis on CPU speed. At one time, there was a direct connection between the speed of the central processing unit and a computer's performance. Generally, consumers expect CPUs with superior numbers to out-perform those with a lower speed. Over the past decade, computer manufacturers have experienced tremendous success in improving the design and performance of other components, such as random access memory (RAM), cache and buses. This has significantly reduced the the overall effect of CPU speed.
  
  

Hertz

• "Hertz" is a timing measurement that is defined in terms of "cycles per second." It is used to measure frequencies, such as sound, electricity or the clock rate of a central processing unit. It is named after the German physicist Henrich Hertz. His research was instrumental in verifying the theory that electricity is actually transmitted through electromagnetic waves. The speed of a CPU is measured by megahertz and gigahertz. The expression, "megahertz," denotes 1 million cycles per second. "Gigahertz" means 1 billion cycles per second.
  
  Both terms are used to calculate the transference speed of electronic mechanisms, including the internal clocks of computers and other devices. For example, a 2 gigahertz computer clock denotes a quantity of bits (32 or 64 CPU words), which are manipulated 2 billion times per second.
  
  

Clock Speed

• When it comes to clock speed, or clock rate, CPU speed, which is often measured in megahertz and gigahertz, can be likened to the speed limit on an expressway. Faster speed limits mean traffic will move faster. The clock rate determines how fast data gets processed by the CPU. CPU words (bits) can be compared to the number of lanes on the expressway. Since more lanes makes it possible for more vehicles to use the road, more bits means more data can move through the CPU.
  
  

Memory

• Random Access Memory (RAM) exercises a significant impact on the CPU speed. Faster RAM transmits more data to the central processing unit. CPU performance is enhanced when it doesn't have to sit idle as it waits to receive instructions and information to process. Slower RAM means the CPU loses nanoseconds of processing time. Designing RAM capable of matching CPU speed would be very costly. To address this issue, computer designers supplemented the slower RAM with smaller, but faster memory called cache.
  
  A cache is a smaller, but faster memory storage device. It contains data recently used by the CPU. Many computers have two levels of cache; level 2 (L2) is located next to the CPU. When the CPU needs to use the data again, it goes to the faster L2 cache, instead of the slower RAM, to retrieve the information. So, instead of sitting idly by as it waits for more data, the CPU is working. The other cache, which is level 1, is the fastest memory available. It is actually integrated into the CPU, and operates at the same speed as the processor.
  
  

Considerations

• Some other tidbits regarding computer speed are: a 2.0 GHz does not process data twice as fast as a 1GHz microprocessor. It is contingent on the amount of work each CPU is cable of completing per clock pulse (cycle). In theory, the 2.0GHz CPU is faster; however, in practice, the 1GHz processor may be more efficient and process more instructions per clock cycle. Less expensive processors may perform one directive each clock cycle. More sophisticated microprocessors typically process multiple commands per clock pulse. Other factors, such as bus speed, network speed and software attributes play roles in CPU speed.