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Clock Speed

Vangie Beal
Last Updated June 23, 2021 7:07 am

Clock speed is the rate at which a computer’s CPU executes instructions. Every computer contains an internal clock that measures the rate a central processing unit (CPU) executes instructions and synchronizes all of the various computer components. The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second. Clock speeds are typically expressed in gigahertz (GHz) or (less commonly) megahertz (MHz).

Like CPUs, a motherboard’s bus also has its own clock speed. Ideally, the CPU clock speed and the bus clock speed should be the same so that neither component slows down the other. In practice, though, the bus clock speed is often slower than the CPU clock speed and creates bottlenecks.

What does a higher clock speed do?

The clock speed of a CPU has as much to do with its performance as the number of cores it contains, so two CPUs with the same clock speed will not necessarily perform equally. For example, a 10-core CPU with a clock speed of 3.8 GHz will be able to accomplish more in a set amount of time than an 8-core CPU with the same clock speed. However, if the 8-core CPU has a higher clock speed than the 10-core CPU meaning each core is able to execute instructions faster it’s possible that the 8-core will have more desirable performance than the 10-core CPU.

It’s worth noting that the need for more cores versus higher clock speed depends entirely on the application being run. To use another example, a video game that runs on a single thread would not benefit from additional cores, but could have a noticeable performance improvement with a higher clock speed. Applications that support multi-threading, on the other hand, would find optimal performance with more cores rather than a higher clock speed.


Overclocking is a technique for running a processor at a higher clock speed than that for which it has been tested and approved by the manufacturer. Typically, overclocking involves manipulating the computer’s BIOS to set a higher clock rate or multiplier. This is not always possible, however, especially in cases where the manufacturer has instituted safeguards against these kinds of alterations. Overclocking is frequently associated with overheating if preventative measures are not put in place. In some cases, a computer’s warranty will not be honored if overclocking is evident.