Overclocking a CPU doesn’t have to be complicated. We’re covering the basics of how overclocking works, why you might want to do it, and the best practices to achieve a stable overclock.1 2
Overclocking your CPU is a great way to extract even more performance from your hardware. The process might seem complex, but the fundamentals of how to overclock are actually pretty straightforward. We’re going to cover the basics of what overclocking is, how it works, and a few ways you can safely do it yourself.
We’ve provided detailed instructions on two popular overclocking methods. The first, and easiest, involves using Intel® Extreme Tuning Utility (Intel® XTU). This all-in-one software does most of the heavy lifting for you, and allows for a streamlined overclocking process that is perfect for first timers.
If you’re looking for a more hands on, customizable approach, you can read about how to achieve a manual overclock using BIOS here. You can also learn how to use Intel® Performance Maximizer (Intel® PM) overclocking software to automatically complete this process for you if you have the latest Gen Intel® Core™ processor.
Otherwise, we’re going to start with the basics and walk you through what you need to know to start overclocking your CPU.
Altering clock frequency or voltage may void any product warranties and reduce stability, security, performance, and life of the processor and other components.
The CPU (Central Processing Unit) is the brain of your PC. It’s a complex and powerful piece of hardware, designed to execute the huge number of calculations each second that help power the modern PC experience.
The computing speed of a processor is heavily impacted by its operating frequency clock, also known as CPU clock frequency, CPU frequency, or clock speed. The higher this frequency, the faster your processor can undertake the high volume of calculations your system requires to properly operate.
The Basics of Overclocking
In order to overclock a processor, the overclocker intentionally increases the CPU operation frequency above the original stock specifications. Because the processor’s frequency heavily impacts the effective computational speed of the CPU, the ultimate goal is to increase the frequency of the CPU in order to achieve faster performance.
The CPU frequency is determined by three factors:
- BCLK or base clock speed. This is the base frequency of your CPU, usually measured in GHz.
- Multipliers or “core multipliers.” There is a single multiplier for each CPU core. These multipliers are applied to the base clock frequency, and the result is the core frequency, commonly measured in GHz.
- Vcore or core voltage. This is the main input voltage to the processor. Higher voltage levels are required to obtain higher stable CPU frequencies, because faster speeds require more power. A higher core voltage also results in a higher heat output, and greater power consumption by the CPU.
Simply put: BCLK x Multipliers = CPU Core Frequency.
Example: 100 MHz (BCLK) x 44 (Core Multiplier) = 4400 MHz = 4.4 GHz. This number, in GHz, is the number you’re most likely to encounter when looking at basic CPU speed specifications.
In order to increase the CPU frequency during an overclock, we will be raising the multipliers in +1 intervals, systematically adding 100 MHz to our processor’s frequency at a time, then testing for success and stability. We will then continue that process until we reach the limits of what is possible with the hardware.
In addition to adjusting frequencies, the overclocking process might require that you raise select voltages, and adjust other performance settings on the system to maintain stability at high frequencies.
The Hardware You Need to Overclock
Now that we’ve covered the basics, let’s explore the necessary hardware you’ll need in order to attempt an overclock.
It’s important that you use an adequate cooling solution when attempting to overclock your CPU. Higher speeds and voltages mean more heat generated by the CPU, and that means a more efficient cooling solution is required for the CPU to safely operate. A capable CPU cooler is critical when attempting to overclock.
You will also need a CPU with a K or X at the end of the name, such as the Intel® Core™ i9-9900K processor. The K-series and X-series suffix designates that the frequency multipliers on the unit aren’t locked and thus allow for overclocking. To learn more about Intel® processor names and designations, check out this breakdown of CPU names.
You will also need a motherboard that allows for overclocking. There’s a large variety of manufacturers to choose from, but you’ll want to look for a motherboard from the Z series, such as a Z390, or from the X-series, such as an X299 motherboard, depending on your CPU. These chipsets have built-in support for overclocking and other features that can further enhance your experience.
To serve various market specifications, it is possible that two identical Z chipset motherboards don’t carry the same features. Make sure to choose the board that’s right for you. You can learn more about how to choose a motherboard here.
Establishing Baseline Performance
Now that you have the hardware, including the right CPU, motherboard, and cooling solution, we can begin the process of overclocking.
The first step is to measure the current performance of your system at stock (default) settings. It’s important to do this before making any changes. This will allow you to easily identify any issues and track any changes in performance.
In order to establish a baseline, you’ll want to use benchmarking software. These software tools estimate the effective computing performance of your system and allow you to track any improvements. Other tools will help monitor vital metrics such as CPU clock frequency, voltage, and temperatures at various stages of the process.
The idea behind this initial system benchmark is to verify that everything is working properly in a pre-overclock state, and to establish a baseline to quantify the performance impact of overclocking. This will provide insight into the system performance and the efficacy of your cooling solution.
Pro Tip: There is no point in overclocking a system which is already overheating. Start all overclocking sessions by assessing the initial state performance of your PC.
Note that an overheating CPU will protect itself automatically and throttle itself down to reduce heat output. This will result in a drop in computing performance and can impact your benchmark results. See this section for more information about safeguards you might encounter.
Here are a few important factors to monitor when running your first test:
- CPU Voltage (Vcore): What is the CPU core voltage during the benchmark? Look at Vcore values under load rather than when idle, as the motherboard may automatically lower this value to reduce power consumption when idle.
- CPU Temperature: What is the maximum temperature reached on all CPU cores (package temperature) during a stress test? Also, what is the temperature of the hottest core? Remember to consider room temperature during this phase, as this can impact readings and the performance of your cooling solution.
- System Power Consumption: What is the maximum power consumption of the system?
- Benchmark Score: What was the final score from your benchmark?
- Overclocking involves keeping track of many different numbers. If you have trouble remembering these measurements, keep track of all numbers in a simple spreadsheet, or go low-tech and write them down on a piece of paper.
- To obtain a more specific baseline score with certain benchmarks, you may have to run them multiple times and calculate an average result.
- Large variations between CPU core temperature readings may indicate cooler mounting issues or an incorrect application of thermal paste.
Starting the Overclock
Now that you’ve got a baseline, it’s time to start actually overclocking. Here, a gradual approach is recommended. You’ll want to make small changes, then test before proceeding. This will allow you to quickly rectify any issues you might encounter, as you’ll easily be able to identify the change that caused the problem.
First Time Overclocking
As mentioned previously, there are multiple ways to undertake the step-by-step process of overclocking. We recommend starting with Intel® XTU, as it provides all the tools you need to benchmark, modify settings, and test system stability.
If you want a greater level of control over performance and settings, you can also overclock your CPU from your PC’s BIOS, though this is recommended for more advanced users. Because BIOS and hardware configurations vary, the step-by-step process might be a little different depending on your system.
Either way, you’ll want to start by adjusting the core multipliers of your CPU to slowly increase target frequency. You will likely observe that some are initially set higher than others. Set all of the available cores to the same value. Here, we used -2 to set all cores to 4.2GHz.
The idea behind this is to set all CPU cores to the same speed to ensure that we run at a precisely set frequency across all CPU cores.
Once you have adjusted your CPU timings and any appropriate voltage adjustments, either with Intel® XTU or through your BIOS, apply these changes and restart your system.
After Attempting an Overclock
After you’ve made changes to your system settings, applied the settings, and restarted your system, you’ll encounter one of two situations:
- Your system is stable, and you’d like to continue overclocking for better performance. If so, repeat the process of increasing the CPU multiplier by +1. Apply the new settings, restart, and proceed to the “Measuring Performance Gains” section.
- Your system isn’t stable, meaning that it crashes or freezes when restarting.
If your system isn’t stable, you have a few options. The first is to raise your Vcore to compensate for the increased frequency, which can help with stability.
When raising CPU core voltage, keep in mind that any additional power running through the CPU will impact its heat output. It’s important to find the lowest stable voltage in all situations, so only increase your voltage incrementally, by: +0.05V at a time, then apply and test until you find a combination of settings that works.
Another option is to lower the frequency by reducing the multiplier value until your system is stable. This might be your only option if you’ve reached a voltage/temperature limit.
Important: When using traditional cooling methods such as air or liquid, never push your voltage beyond 1.4V. Always make sure to keep your maximum CPU temperature below 100°C for temporary bursts, and 80°C or below for longer workloads.
See the “Manage Power Consumption and Heat” section for more details on CPU temperature limits.
You will eventually reach your system’s limitation as far as frequency/voltage/temperature. This limit is going to be different for every system.
Once the upper threshold has been reached, your options are to:
- Try overclocking the CPU cache. This utilizes the same principles as above, only using the CPU cache multiplier.
- Try overclocking the RAM. Memory speed can have a considerable impact on performance. You can read more about how to overclock RAM here.
- Upgrade to a better cooling solution.
- Examine whether safeguards are throttling your performance, and decide if you feel confident in adjusting these. You can read more about safeguards below.
Once you’ve applied the changes and your system successfully restarts, it’s time to see what’s changed and verify stability and performance.
Measuring Performance Gains
Effective performance measurement is the cornerstone of any successful overclock. It’s the only way to measure performance gains.
Earlier you obtained your baseline performance metric by running a benchmark test. It’s now time to run the same test again and compare scores.
Overclocking is an iterative process. If this is the first attempt, the gain in performance might not yet reach your goal. This is normal. With each successive performance tweak, you will gradually move closer to your performance objectives.
Once you’ve run your benchmark again and compared scores, you can either move on to ensuring stability or continue to modify settings in order to improve performance.
Pro Tip: Voltage settings are an important part of overclocking, but using too little or too much can result in instability. Consider changing it in small steps (e.g +25-50 mV out of 1.1 V range) to see how the hardware reacts. Take note of the temperature after any voltage change.
Power Consumption and Heat
Monitoring power consumption and heat are critical parts of the overclocking process. At this stage, your cooling solution will play a large part in whether you achieve a successful overclock.
Be aware of the upper temperature limit of your CPU, as well. To find out the maximum allowable temperature of your CPU, go to this page and find your CPU’s “Tjunction.” In the example below, you’ll see that an Intel® Core™ i7-9700K processor has a temperature limit of 100°C. You don’t want your CPU at or even near this temperature when under load. Around or under 80°C is ideal for most CPUs during normal operation, so be sure the results of your overclock reflect that.
When temperatures exceed the specified Tjunction limit, there is a risk that the heat can damage the processor. Even though safeguards exist to mitigate the risk, you always want to find the lowest possible temperature for any given performance setting to ensure the longevity of your CPU.
When overclocking, you’re pushing the limits of your hardware. As a result, it’s possible that your system will eventually become unstable during this process. System instability may manifest through:
- Blue screen error message
These issues mean that you have encountered an imbalance in your settings. Don’t panic; this is a normal part of the testing process as your system pushes to its limits. You can simply restart your system using the reset button, or power off/on if the reset switch is not responsive.
From here, there are three possible outcomes:
- The system does not boot up, even after powering it off/on. In this case, you must Clear CMOS—that is, erase the BIOS settings to reset the motherboard to its default configuration and restart. If this still doesn’t work, try troubleshooting with these strategies.
- The system does restart. When the system crashed, it had not yet reached the maximum temperature limit. In this case we can raise our processor Vcore slightly and try again. Don’t add more volts than necessary, as it will result in more heat output and potential strain on your CPU.
- The system does restart. When it crashed, it had reached the critical temperature limit, and safeguards kicked in to protect the CPU from overheating. You have found the limit of your system’s cooling solution. In this case, it’s recommended to reduce the operating clock frequency of your processor to fall back to a more stable state within an acceptable temperature range. To do so, you may have to reduce the CPU Vcore, upgrade to a more robust cooling solution, or look at other settings than can result in an increase of performance with little impact on temperatures such as CPU cache, memory frequency, memory timings, or OS optimizations.
The final step of the overclocking process involves verifying long-term system stability. Just because your system restarted and didn’t immediately crash doesn’t necessarily mean it’s ready for 24-hour use.
To establish whether the system is truly stable, it’s necessary to run longer and more intensive stress tests. Specialized software applications allow us to check long-term stability of our system under a variety of workloads. Head here to learn more about stability testing and stress testing software.
Playing It Safe
Modern PC hardware is usually designed with safeguards to protect the system from potential damage due to power fluctuations or excess voltage.
When overclocking, you may encounter these integrated defenses, many of which originate from the power supply of the system. You may be able to disable or modify the parameters of these safeguards, but this is not recommended unless you are very confident in how to proceed, as you could potentially damage the hardware.
Here’s a quick overview of some of the safeguards you might encounter:
Over Temperature Protection (OTP): This safeguard limits the CPU temperature to a pre-established maximum. If the system temperature is too high, your PC will automatically throttle the CPU (reduce its frequency) to bring temperatures back to safe levels. This will result in a drop in CPU performance. If this thermal throttling still isn’t enough to sufficiently reduce temperatures, the system will automatically shut down.
Over Power Protection (OPP): Motherboards are designed to sustain a certain level of power throughput. If your CPU’s power consumption is too high, your system will activate this safeguard. Similar to OTP, this will reduce your system clock in an effort to reduce temperatures, and eventually shut down the system if it is not successful.
Overcurrent Protection (OCP): This is another safeguard present in all PCs. Current increases inside your CPU as voltage and frequencies go up. With certain motherboards, there is an option to change this value. (In Intel® XTU it can be done though the “Processor Core ICCMAX” setting. You will most likely have the same option in the BIOS.)
Over Voltage Protection (OVP): This activates when the CPU input voltage is too high.
Under Voltage Protection (UVP): This is the functional opposite of OVP. Here, your system will shut down if the CPU voltage is too low.
Short Circuit Protection (SCP): This activates when the motherboard detects a short. There’s rarely a reason to deactivate this safeguard.
Overclocking Software and Tools
To achieve a successful overclock, you’ll want the support of software to streamline the process. Software can help with safely modifying settings, benchmarking and testing, and monitoring and stress testing your system to ensure stability. In the following section, you’ll find a brief introduction to some of the essential tools and software utilities that make up the overclocker’s toolkit.
This list isn’t exhaustive, but it will provide a good starting point.
The BIOS (Basic Input/Output System) is the software that runs on your motherboard. (It may also be called the UEFI [Unified Extensible Firmware Interface] in newer motherboards.) Effective at a level below your operating system, the BIOS manages the motherboard and allows for communication with all installed hardware.
The BIOS is also where you can adjust the performance parameters of your hardware, including your RAM, storage, and CPU.
It’s important to note that the visual presentation of BIOS varies depending on the motherboard manufacturer. To access the BIOS, you’ll need to press a specific key, such as F2 or Delete, moments after switching on your computer and before the Windows* loading screen appears. Refer to your motherboard documentation for specific instructions.
Intel® Extreme Tuning Utility (Intel® XTU)
One exceptionally robust overclocking tool is Intel® XTU. This software combines some of the most important features you want when overclocking into a single application.
Intel® XTU detects and monitors hardware, tests stability, helps with overclocking, and can run benchmarks. The layout is simple and provides the essential functions required for intermediate overclockers.
CPU-Z* by CPUID is a simple and lightweight application that provides essential info about your processor, motherboard, and RAM. It‘s recommended for beginners as well as experts that require a straightforward monitoring solution.
3DMark* by UL Benchmark is a benchmark utility that includes two processor tests and combined CPU and GPU workloads. 3DMark is a great choice of benchmark to measure the overall performance of a PC, especially for gaming workloads.
Now that you have a sense of how to overclock, you’re ready to get the most out of your CPU.
Here are a few key principles to keep in mind when overclocking:
- Don’t rush. Change one setting at a time, then test before continuing.
- Always keep an eye on CPU temperature, and keep it as low as possible while preserving stability.
- Never use more CPU voltage (Vcore) than necessary.
- Never modify settings or safeguards that you don’t understand.
With these four principles in mind, your overclocking experience should be fun, safe, and beneficial. Enjoy that faster clock speed!