Fact Checked

What is a Clock Rate?

Emma G.
Emma G.

The clock rate, or clock speed, of a computer is the rate at which a central processing unit (CPU) is able to perform basic functions. It is normally measured in megahertz, or millions of cycles per second, or even gigahertz, which are billions of cycles per second. The clock rate is useful for comparing the speed of chips made by the same company, but is not a reliable way to compare different types of computers because many other factors can determine the speed of a computer. Instead, computers should be compared based on how quickly they perform specific tasks such as loading graphics or performing calculations.

All computers have clocks that emit regular electrical pulses to help the computer synchronize the timing of tasks it is asked to perform. The CPU requires a certain number of clock cycles, or pulses from the computer's clock, to execute a command. The number of cycles a computer can achieve in a second determines its clock rate. The first PCs created by IBM in the early 1980s had a clock rate of around 4.77 MHz, which is about 5 million cycles per second. By 2010, the clock rate of the average computer could be measured in GHz.


Though clock rate most commonly refers to the speed of the CPU, other devices in a computer also have a clock. Expansion buses, which allow the computer to be modified using printed circuit boards, are governed by internal clocks. Random access memory (RAM), the read and write memory used to perform work while the computer is running, uses a clock as well.

In computers, the clock rate of the central processing unit is measured in GHz.
In computers, the clock rate of the central processing unit is measured in GHz.

The CPU can only process as quickly as the other components in the computer allow. If the expansion bus or the RAM are slower than the central processing unit, the computer will not run as quickly as the CPU allows. In addition, some processors may perform different tasks at different rates. For example, one may be able to divide two numbers in 12 cycles while another takes 20 to perform the same task. For this reason, clock rate is not a reliable way to compare computers.

Benchmarks are a more reliable source of comparison. Several organizations offer reliable and monitored industry standard benchmarks. These include Standard Performance Evaluation Corporation (SPEC), the Transaction Processing Performance Council (TPC), and the Embedded Microprocessor Benchmark Corsortium (EEMBC). These companies run computers through a series of closely controlled tests to determine how quickly each one performs specific tasks. The numbers are published free of charge on organization websites.

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Discussion Comments


@hamje32 - That’s not for me. Computers are plenty fast nowadays. However what most people don’t realize is that RAM has as much to do with performance as clock speed, in my opinion.

If you increase your RAM size, then you can offload a lot of your programs into RAM instead of on your hard disk. The advantage of this is that it’s faster to access RAM than it is to access the hard drive.

I think you should just max out your RAM and see if that doesn’t boost your computer’s speed. It won’t affect your processor speed obviously but you will get faster performance overall.


I know that there are some people in the computer gaming community for whom clock speeds have become a kind of holy grail in their own right. These gamers do something called “overclocking,” where they push the processor speed of the computer’s CPU just a little bit more than its official specifications allow.

I have absolutely no idea how they do this, but it’s a common practice among the hard core gamers. It’s not without its dangers however. For one thing, increasing the CPU of the computer causes it to heat much hotter.

As a result, the overclockers have to cobble together a bunch of cooling fans and even miniature air conditioning setups just to deal with the increased heat of their computer.

The other danger is that the CPU could just burn up altogether. That seems to be a danger that these gamers want to take, intent as they are in pushing their computers’ performance beyond the bleeding edge.


@myharley - There are some online software programs where you can do a CPU speed test on your computer.

It doesn't take very long, and you can know what the real speed of your CPU is. I have seen some where you download some software to check your speed.

There are other sites where you don't need to download anything and can check your speed directly from that site.

That is the one I usually use when I want to know how fast my processor is running.


It seems like no matter what I do, I have a slow CPU speed. When I bought a new computer I even had them delete all the pre-loaded programs that came with it so they wouldn't take up so much space.

Even with a new computer and dual processors, I thought my computer speed would be faster than it is. I usually have a lot of windows open at once, and I know that can affect the clock rate speed.

I live in a rural area so can't get high speed internet, so wonder if any computer I get I would have about the same speed.

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    • A CPU.
      By: NorGal
      A CPU.
    • In computers, the clock rate of the central processing unit is measured in GHz.
      By: Restyler
      In computers, the clock rate of the central processing unit is measured in GHz.