When shopping around for a processor, the first numbers that jump out at you would probably be such numbers as “1.8 GHz, 2.8 GHz, 3.0 GHz, etc.” These numbers all represent clock speed and have been used for quite some time as a metric for measuring CPU performance. But are they accurate? Is clock speed still a good measure of performance for modern CPUs? Let’s find out.
The speed of a processor is determined by the amount of time it takes to generate pulses. These pulses represent the time it takes to execute basic instructions, which is known as its clock cycle. When measuring the frequency in which the CPU can complete clock cycles, you get the CPU clock speed.
The CPU clock speed is represented using the SI unit Hertz (Hz) – generally in megahertz (MHz) or gigahertz (GHz) – which shows the number of clock cycles completed per second. A CPU with a 2.5 GHz clock speed, for example, means it can complete 2.5 billion clock cycles within one second.
Generally speaking, a higher clock speed suggests that it can process a higher volume of data in less time, which would indicate that it performs at a higher level. At first glance, a CPU with a clock speed of 3.0 GHz does look faster compared to a CPU with a clock speed of 2.5 GHz. But in recent years, this has no longer been the case.
In the past, computer processors only worked with a single, static clock speed. The technology was limited, which meant you needed to upgrade to a better CPU to improve performance. This concept was rendered obsolete with the introduction of dynamic CPUs.
The advent of dynamic CPUs brought about such concepts as CPU performance boosts and performance scaling. This meant that processors no longer had to work with a single speed but with a dynamic range of frequencies. This introduced three main frequencies, namely the processor base frequency, maximum turbo frequency, and the idle frequency.
Base Frequency. The processor’s base frequency describes its ‘maximum’ clock speed when working at a normal level at sustained periods. By normal levels, we refer to speeds under normal loads without exceeding the set thermal design power (TDP). It also sets the minimum speed that the CPU can guarantee while working without going over the set limits. You can find this metric on the CPU’s description as the advertised clock speed. For instance, the Intel Core i7-8750H processor has an advertised clock speed of 2.2 GHz, which is also its base frequency.
Maximum Turbo Frequency. The maximum turbo frequency refers to the maximum level at which the CPU can perform under heavy load. When complex programs are used, the CPU automatically draws more power (within a set upper limit), which also increases temperature. This enables the CPU to run at a much higher clock speed than the base frequency. Using the same example as earlier, the Intel Core i7-8750H has a maximum turbo frequency of 4.1 GHz.
Idle Frequency. The CPU’s idle frequency refers to the minimum clock speed at which the processor performs, below the base frequency. In contrast to the maximum turbo frequency, the CPU’s idle frequency is reached when the computer is under a light load. It draws less power than normal, which enables the CPU to work at a much lower clock speed. The Intel Core i7-8750H has an idle frequency of 0.8 GHz.
The technology behind dynamic CPU performances improves the efficiency of modern processors. As mentioned above, CPUs in the past could only work with a single clock speed no matter the load. This meant that under light loads, the CPU draws in more power than it should. At heavier loads, the CPU performs at a lower clock speed that required.
With dynamic CPUs, the processor automatically adjusts its clock speed to match the current operating environment, which improves its efficiency. It enables the CPU to work at an elevated level under an increased workload, or at a lower level when the full performance is not needed, which conserves energy.
You can manually override your CPU clock speed settings to give your system a much-needed boost. By manually tweaking clock speed, you can boost CPU performance at an even higher level than the maximum turbo frequency. This is called overclocking.
Overclocking enables the CPU to handle even more complex instructions without any need for an upgrade to a better component with an even better architecture. For instance, your Core i7 processor with a base frequency of 2.6 GHz and a maximum turbo frequency of 4.0 GHz may be set to operate at 6.0 GHz, given the right tools.
While the biggest reason for overclocking may be to speed up your computer, there are also plenty of other reasons why you shouldn’t do it.
If you do still want to overclock your CPU, take careful note of the following:
The introduction of dynamic CPUs and Turbo Boost technology has vastly improved the efficiency of modern processors. Instead of working with a single speed regardless of the load, processors are now able to adapt. They are now able to draw more power to work at an elevated state when under a heavy workload. They are now also able to work at idle speeds and draw less power when the workload is light. Clock speed has become dynamic. But the performance it delivers may still not be enough. In such cases, you can manually override the clock speed through overclocking. Just make sure your system can handle it.