Here’s Why Your CPU Clock Frequency Keeps Changing

Overclocking (running your CPU at a higher clock frequency that it’s rated for) used to be something of a badge of honor for performance-tuned PC builds. However, times have changed and now your CPU clock speed changes might be an automatic feature, or a sign of trouble instead of power.

Your CPU’s clock speeds might be changing due to performance settings, overclocking, or heat mitigation failures. You can fix these issues by disabling any boosts or overclock so and checking on your CPU’s heat mitigation. Overclocking doesn’t always give the boost that it used to, and might even cause performance issues for tuned PC builds.

Let’s get in control of your CPU’s clock speeds.

What Is CPU Clock Speed?

Before we get into why your CPU’s clock speed keeps changing, we should quickly cover what clock speed is and why it matters.

Clock speed simply means the number of calculations your CPU can make each second. In more technical terms, the clock speed, or frequency, represents the number of cycles that a CPU can process each minute. Today’s CPU’s measure these per-second cycles in the billions.

An Intel N5030 CPU with current clock speed of 2.31 Ghz the base frequency is 1.10 GHz and the burst is 3.10 GHz
An Intel N5030 CPU with current clock speed of 2.31 Ghz the base frequency is 1.10 GHz and the burst is 3.10 GHz

Each of these cycles handles the basic mathematics that undergird the entirety of computing. Your CPU is basically the “brain” of your computer and the clock speed is how fast it can “think.” Every cycle handles a single basic equation and some can even handle multiple at once.

The clock speed of your CPU used to be one of the most important factors in the overall performance of your PC. However, today’s multi-core processors have made the base CPU clock speed less vital than it once was. It’s still important, but there are now factors that can change how powerful clock speed is.

A modern CPU with a slower clock speed than a CPU from 5 years ago might still be faster. This is because the modern CPU can take advantage of multiple cores and improved programming that makes more efficient use of a slower base speed.

Now that we’re up-to-speed with our CPU basics, let’s get into why your clock speed keeps running up and down.

Why Is My CPU Clock Frequency Changing?

A Ryzen 9 5900X Zen3 CPU
A Ryzen 9 5900X Zen3 CPU

There are basically three things that impact the clock speed of a CPU. Automatic performance boosts, overclocking, and thermal throttling are the big factors that can raise, or lower, your CPU clock speed.

Here’s a more detailed explanation of those factors, and whether you even need to do anything to regain control of a runaway CPU (not all CPU frequency changes are a bad thing, after all).

Automatically Boosted CPU Performance

Overclocking used to be the work of dedicated PC performance buffs, but it now comes standard in most PC packages. Your PC hardware likely came with software or firmware that can automatically boost the speed of your CPU. Modern CPUs like Intel Turbo Boost and AMD Precision Boost can increase the speed of your CPU, either across a single core – or multiple cores.

And this is the most common reason that the CPU speed is constantly changing, especially on a newly built (or purchased) PC which hasn’t been subject to heavy running yet. Take my simple Asus Chromebook for example – it has a 4-core CPU, and it’s CPU clock speed constantly changes:

An Intel N5030 CPU on a Chromebook with a constantly changing CPU clock speed
An Intel N5030 CPU on a Chromebook with a constantly changing CPU clock speed

Notice how the “Current speed” is constantly changing? This is despite the fact that Intel’s own website listing (for the N5030 CPU) doesn’t mention a clock of 2.(something) GHz anywhere:

Information from the Intel website about a CPU with a base and burst frequency
Information from the Intel website about a CPU with a base and burst frequency

This is known as Intel Turbo Boost, and it basically means that all four CPU cores will start out at 1.10 GHz. Whilst this is a very low clock frequency, running this slowly will help preserve power consumption. There’s no point in a CPU always running at a max speed, even when no-one is touching the computer, after all.

However when you start using your computer (or laptop/chromebook) and opening up programs, a clock speed of 1.10 GHz would be pretty slow. So the CPU is designed to automatically boost itself, up to a max of 3.10 GHz (in this CPU’s case). This basically means that the CPU can effectively overclock itself, to run faster than it’s basic speed when required.

This is now a common feature of CPUs (including in Apple computers, smartphones and other devices), and it is why you’ll often see a different CPU clock speed in Windows Task Manager and similar programs:

The current CPU speed of 4.34 GHz along with the base speed listed at 3.70 GHz
The current CPU speed of 4.34 GHz along with the base speed listed at 3.70 GHz

Usually this process works seamlessly and without issue, but if you experience problems, you might not want to risk the extra heat and power drain that comes with boosted performance.

How To Disable Turbo or Precision Boost

The good news is that it is relatively easy to turn off these included speed boosters. All you need to do is head over to your system’s BIOS and disable the performance boosting settings. Here’s how you get it done.

Note: the below information relates to a typical PC build, with Windows installed on it. It’s often possible to disable Intel Turbo Boost or AMD Precision Boost on laptops and Chromebooks too, but in that case it’s worth looking online for specific guides for your model.

To enter BIOS on a Windows PC, all you need to do is hold the “shift” key while clicking on “restart” in the start button menu. This is a recent shortcut built into modern windows computers.

You can also use the command prompt to get that elite hacker feeling. All you need to do is head over to your command prompt app and select the “run as administrator” option.

Once the command prompt is open, just type “shutdown /r /fw” without the quotes and your PC will send you a notification that it is about to shut down. This command prompt line works by using the “shutdown” command with some adding instructions to restart and boot into the BIOS menu.

Once you’re in the BIOS menu, you’ll need to find the section that governs your built-in speed boost. This is typically under menu headings like “System Configuration” and “Performance Settings.”

You’ll want to find and disable any setting like the Intel Turbo Boost or the AMD Precision Boost we mentioned earlier. These are boosting your CPU speed and could be causing your clock speed swings.

Whilst every BIOS is different depending on the type of motherboard you buy, here’s a recap of the general process you will need to follow:

  • Restart to your BIOS menu
  • Enter System Settings (sometimes called Advanced Settings)
  • Navigate to Performance Settings (sometimes called CPU Settings)
  • Disable any speed boost options that are present

The below YouTube video shows how to disable Intel Turbo Boost on an MSI motherboard:

Overclocking

Overclocking used to be the terrain of DIY PC buffs, but it’s now a built-in feature. However, you can still do a DIY overclock on top of the built-in overclock, or boosting, that most motherboard’s ship with.

Unless you really know what you’re doing (and always need every core running quicker), this DIY overclock usually doesn’t give you much additional power. We’re talking fractions of what your CPU is already putting out. That built-in boost covers what would have been the range that pre-boost DIY overclockers were after.

However, that additional boost could still get you some gains in your PC’s performance. Your PC might be overclocked beyond its boosted limit by a previous owner, a forgotten overclocking attempt, or even on accident thanks to overclocking and performance utility tools.

Those utility tools are where we will start our fix for CPU clock speed problems. Tools like Intel’s Extreme Tuning Utility or the Ryzen Master from AMD can overlock beyond their CPU boost features. A quick fix is to open these tools (or install them first, if you don’t already have them) and reset any changes to CPU speed.

You should also reset your BIOS settings. The easiest way to do this is to head into your BIOS menu using the instructions we laid out above and reset any changes to performance. If you have bought your computer second hand, resetting the BIOS back to its factory default might be the best idea.

You can also change this by resetting your BIOS by manually resetting your motherboard. Your MB’s manual will tell you where the reset button is located, but you could also just pull the CMOS battery for 30 seconds, reinstall the battery, and that should reset your BIOS to a pre-overclocked state.

CPU Thermal Throttling

Thermal paste TIM put onto the AMD Ryzen CPU
Thermal paste TIM put onto the AMD Ryzen CPU

The last thing to consider is that your CPU might be getting too hot.

When a CPU overheats, it cuts back on power and performance to quickly drop the temperature. From the hardware’s perspective, it’s better to slash performance abruptly than it is to burn out your CPU.

Your CPU could be overheating for a variety of reasons ranging from malware all the way over to an improperly installed CPU fan. CPU temperatures can also be affected by the overall heat mitigation of your PC.

Is CPU Clock Frequency Changing A Problem?

With all this said, are CPU clock speed changes even a problem?

They might not be. They might just reflect your CPU usage. A changing clock speed could be related to higher periods of use like intense gaming or running video editing software.

On the other hand, it could be a sign of heat mitigation failure or improperly tuned settings. These could cause you some performance loss or they could even cause heat damage to your CPU.

In short, staying on top of your CPU clock speed can help you better manage your performance and the longevity of your PC.

How to Fix CPU Thermal Throttling

The top fan of my Noctua NH C14S CPU cooler for my AMD Ryzen CPU
The top fan of my Noctua NH C14S CPU cooler for my AMD Ryzen CPU

Here’s a few things you can do to trouble-shoot CPU thermal throttling in order from easier to hardest.

  • Check your Activity Monitor to see if any unknown, or known, programs are spiking CPU usage
  • Run your antivirus software for a sweep
  • Check your CPU’s temperature using an included CPU temp monitor or by downloading a new one
  • Check your CPU’s heat mitigation, usually a fan or a liquid cooling system, for any malfunctions that could be failing your CPU’s heating needs
  • Consider replacing any old, or brand-new, parts as they might be failing or defective

Basically, you should start by checking the software side of things (such as the programs that are running, and for viruses). If that looks fine, you may need to open your computer case and start digging around.

The cause might be one of a number of things, but thankfully the most expensive parts of your computer (such as the CPU and motherboard) are unlikely to be the issue. Double check that your chassis fans are still running, and that your CPU cooler is still mounted correctly (especially if you recently moved your computer, since it might have become a bit loose).

Should You DIY Overclock Your CPU?

You could try overclocking your CPU on your own, but you might run into a lot of trouble for very little gain.

Today’s CPUs are built for both performance and general use. The included boost and tuning features allow users to overclock safely without doing too much tinkering. They put the BIOS settings in convenient menus you can play with without risking changing much more vital settings.

CPUs are also already built within certain spec ranges. Your base and boosted clock speeds represent a range of performance options that cover basic needs and high-end computing. The gains from overclocking beyond these limits are going to be reserved for specialist needs.

Even gamers with high-demand software might not see much benefit from overclocking beyond the boost. Those extra cores in your gaming CPUs only make overclocking benefits all the more marginal.

Overclocking does get you more performance, but we live in a day and age where those boosts are less vital than they used to be. Why risk the extra heat damage?

cropped A picture of me Tristan
About Tristan Perry

Tristan has been interested on computer hardware and software since he was 10/11 years old. He has built loads of computers over the years, along with installing, modifying and writing software (he's a backend software developer 'by trade').

Tristan also has an academic background in technology (in Math and Computer Science), so he enjoys drilling into the deeper aspects of technology.

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