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How to Overclock Your CPU

Abby Braden
Last Updated September 8, 2021 9:29 am

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Overclocking means to run a PC’s microprocessor faster than the clock speed for which it has been tested and approved. Overclocking is a popular technique for getting a performance boost from your system without purchasing additional hardware.

How does overclocking work?

Overclocking essentially increases a component’s clock rate to a higher speed than what it was designed for. The clock rate is the frequency at which the clock generator generates pulses, which is used to synchronize the operation of its components. 

Overclocking really only applies to the CPU or GPU, but other components can be overclocked. You can increase the CPU’s speed by setting a higher clock rate in the computer’s BIOS (tutorial below), which forces it to perform more operations per second. While this speeds up your CPU, the CPU will produce additional heat and may become physically damaged if you don’t provide additional cooling. 

How effective is overclocking?

Most times overclocking will result in a performance boost of 10 percent or less. For example, a computer with an Intel Pentium III processor running at 933MHz could be configured to run at speeds equivalent to a Pentium III 1050MHz processor by increasing the bus speed on the motherboard. Two identical systems being overclocked most likely will not produce the same results. One will typically overclock better than the other.

Can I overclock Windows, Mac, Linux? 

For the most part, overclocking is limited to Windows computers. While it’s possible to overclock a Mac, most macOS laptop or desktop machines don’t have the cooling required to keep internal temperatures at an acceptable level. While you could overclock a Mac, there isn’t a huge amount of performance to be gained, and the risks outweigh the potential benefit. 

As for Linux, overclocking should be avoided, as Linux tools do not show the correct overclocked frequency. With Windows, there is a plethora of monitoring and benchmarking tools available, but with Linux, these kinds of choices are not available. 

A CPU with a 10x multiplier will thus see 10 internal cycles (produced by PLL-based frequency multiplier circuitry) for every external clock cycle.

To that point, many motherboards and Intel CPUs have locked multipliers, preventing users from being able to overclock. A multiplier sets the ratio of an internal CPU clock rate to the externally supplied clock. For example, a CPU with a 10x multiplier will see 10 internal cycles for every external clock cycle. While most manufacturers lock this setting, Intel sells some CPUs with unlocked multipliers. 

Benefits of overclocking your CPU

The most obvious benefit of overclocking is the increase in operations per second, a standard unit measuring the calculation speed of a computer processor. However, overclocking has become less critical over time. In the past, the process created a more responsive desktop and faster performance in Microsoft Office, but now computers are so powerful that users likely won’t notice a difference. 

Gamers or computer enthusiasts that want their hardware to run as quickly as possible will find overclocking still valuable. Along with higher performance and system optimization, it can be cheaper to purchase a lower performance component and overclock it to the clock rate of a more expensive component. Overclocking can also extend the life of older equipment. 

Cautions to take when overclocking your CPU

Higher clock rates and voltages increases power consumption, meaning electricity cost and heat production also increases. Higher heat production means that fans running at max speed for the required degree of cooling can be noisy. 

An overclocked computer may also become unreliable. The device may appear to work without problems, but when applications such as Microsoft Windows are reinstalled or upgraded, error messages or even the blue screen of death could occur. In addition, overclocking may void your warranty. AMD, Intel, and many motherboard manufacturers typically do not cover overclocking. If you’re concerned, check the warranty before going through with the process.  Read also: What is a CPU Cooler?

How to overclock your CPU

Because you can change settings such as voltage and frequencies from your computer’s BIOS, it’s the only reliable way to overclock your system. Before you begin the process, update your BIOS to the latest version. The look and layout of each BIOS varies depending on the motherboard manufacturer.

  1. Establish baseline performance

    Before overclocking, it’s important to measure the baseline performance with a benchmarking utility. This will allow for easy comparison of the performance after overclocking. 

    There are no benchmark utilities in BIOS, but there are benchmark tools available that open from Windows, such as CPU-Z or HWMonitor.
    Interface of HWMonitor, a tool used to safely overclock a computer.
    Once you have your benchmark score, keep track of it to compare it with later scores after overclocking the CPU.

  2. Access BIOS

    As mentioned previously, every BIOS configuration is different, so the location and name of the settings may vary. When in doubt, Google what the setting is called on your specific motherboard to find the equivalent. 

    To access the BIOS, turn off your computer and turn it back on. As the computer restarts, press the Delete, F2, or F10 key repeatedly (depending on your manufacturer). This will allow you to enter the PC’s BIOS controls. You’ll likely need to enter Advanced Mode or a similar option.

  3. Adjust the CPU Multiplier

    Once in the BIOS, the first step in overclocking is to adjust the core ratio (also known as clock ratio), which is one of the values that determines the final speed of the CPU. The CPU’s clock speed is determined by two values: the base clock (almost always set at 100 MHz) multiplied by a multiplier. 

    So to overclock, we will change the multiplier number. Find the Core Ratio controls in your BIOS. If there’s an option to Sync All Cores, select that before continuing.

    How to change the core ration limit to overclock a computer.
    Increase the Core Ratio Limit upward by one value or .5 of a value, such as from 43 to 43.5. The full potential of the CPU is typically reached between 40 – 50, resulting in an overclocked speed of 4 to 5 GHz. Since the multiplier adjustment isolates the overclock to just the processor, it can deliver more speed than base clock boosts.

  4. Adjust core voltage

    Many voltage parameters affect a CPU’s operation, but the most impactful is the core voltage. Core voltage helps stabilize the overclock, and it may need to be modified after changing the core ratio settings.

    The core voltage settings should be located near the core ratio settings and is usually called CPU voltage or CPU VCore. Modifying this ensures the CPU has the power it needs to run at the higher core ratio speeds since higher frequencies require more power. 

    Use Google to see what VCore settings are typically used for your specific motherboard. Important note: Be cautious when adjusting CPU voltage. Setting the number too high can result in killing the CPU. It’s important to find the lowest stable voltage, so increase your voltage incrementally, no more than +0.05 V at a time. 

    Find a combination of core ratio and voltage that works, apply the changes, save and exit your BIOS, and restart your system.

  5. Measure performance gains

    If the computer fails to restart or crashes, go back to BIOS and return to the last known variable setting.

    If the boot is successful, run the same benchmark program you ran prior to overclocking your system to see if the score has improved. If the numbers have improved, you’ve successfully overclocked your CPU. If you are satisfied with the performance gain, leave your ratio numbers where they are. If your changes don’t result in performance gain or you are unsatisfied, go back to BIOS and continue to adjust the settings until you achieve the results you’re looking for.

  6. Run a stress test

    Once you’ve reached the ideal combination of settings, it’s a good idea to run a stress test to ensure your system has stability over longer periods of time. This test will generate heavy loads on your components while checking for errors and detecting stability issues. There are several stability software options available, such as OCCR, but choose one that most closely mirrors the way you use your computer. 

    If you’ve run your stress test and the system is stable, you’ve successfully overclocked your CPU and created a system that is running faster than before. 

Read next: SolutionBase: How overclocking works