BIOS (Basic Input Output System), is the software installed on your motherboard that loads before your operating system. It provides an interface that allows you to configure the hardware installed into your motherboard. Because you can change settings such as voltages and frequencies from the BIOS, it is possible to use it to manually overclock your CPU in order to achieve a higher clock speed and potentially better performance.
This article assumes you have a basic understanding of what overclocking is, and how it works. If you’re new to overclocking and want to learn more about the fundamentals, check out this overclocking overview to get up to speed.
You’ll also want to make sure you have the right hardware.
Before attempting BIOS overclocking, it’s worth considering software options that simplify the process. Intel® Extreme Tuning Utility (Intel® XTU), for example, is an easy-to-use option for people who are new to overclocking. An even simpler automated option that will work with the latest Intel® Core™ processors is Intel® Performance Maximizer (Intel® PM), which you can read about in detail here.
Overclocking from BIOS, on the other hand, offers the most complete access to all available system performance settings. If you’re interested in manually fine-tuning your system settings and managing every aspect of your overclock, you should do it through the BIOS.
Before you begin the process, be sure to update your BIOS to the latest available version. This will allow you to take advantage of any new features or fixes the motherboard manufacturer has released. Search for your motherboard online or consult the appropriate documentation to determine how to properly update your BIOS.
The look and layout of each 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.
Altering clock frequency or voltage may void any product warranties and reduce stability, security, performance, and life of the processor and other components.
Settings to Know for Overclocking
BIOS provides system-wide hardware access, and as a result contains extensive menus to navigate. The design of the BIOS can also vary depending on the motherboard manufacturer, so precise names or menu layouts may vary as well. Check online resources to search for the location of the feature you’re looking to adjust, or explore the options in your BIOS until you find what you’re looking for.
Here is a list of some of the most useful settings for overclocking:
- CPU Core Ratio, or multiplier, determines the speed of your CPU. The overall speed of your processor is calculated by multiplying the base clock speed (BCLK) by this ratio. For example, a BCLK of 100MHz multiplied by a CPU core ratio of 45 would result in a CPU speed of 4,500MHz, or 4.5GHz. This setting can usually be changed per core or across all cores.
- CPU Core Voltage is the amount of power being supplied to the CPU. Increasing CPU Core Voltage increases the input voltage for your CPU, providing the CPU the headroom it needs to run at higher speeds.
- CPU Cache/Ring Ratio adjusts the frequency of certain parts of the CPU, like the cache and memory controller.
- CPU Cache/Ring Voltage is designed to increase the input voltage of your CPU cache. This helps to stabilize your processor’s overclock. On some platforms, this voltage is linked to the CPU core voltage, and can’t be modified separately.
Monitoring System Vitals
You’ll want to monitor your system carefully when overclocking, as making changes to the power supplied to your hardware can impact operating temperature.
The BIOS offers limited system monitoring options, so a better bet is using software that runs from Windows. Intel® XTU offers a full suite of system monitoring tools, and there are other options available as well, such as CPU-Z, CoreTemp, HWiNFO32, and more. Read more about system monitoring software here.
Now that you understand the settings you’ll be adjusting, let’s start by benchmarking your system.
Step One: Establishing Baseline Performance
The first step in the overclocking process is measuring the baseline performance of your system with a benchmarking utility. This will allow easy comparisons to the performance metrics after the overclock, clearly illustrating any improvements. Because you cannot run a benchmark utility from BIOS, you’ll want to use a benchmarking utility that opens from Windows.
Once you have your benchmark score, make sure you keep track of it, so you can compare it with later scores and see the results of your work.
Step Two: Adjusting Performance Settings
As mentioned above, every BIOS and hardware configuration is different, so the location of your settings may vary. The basic tenets of overclocking are the same across systems, however.
The first setting you’ll want to modify is the CPU Core Ratio, which is one of the values that determines the final speed of the CPU. Find the section in your BIOS that allows you to adjust this setting.
Caution: When changing a CPU’s operational settings, it’s best practice to change one setting at a time, and then verify that it was successful before changing another. This way, if there are any issues, it will be easy to identify the setting that caused it, and revert to the last known functional settings.
When you find it, begin by adjusting the CPU Core Ratio upward, usually by one value (for example, from 42 to 43). Then apply the changes, save and exit your BIOS, and restart your system.
Whenever adjusting any settings in your BIOS, adjust in the smallest increment possible. Then apply the changes, restart your system, and run your benchmark. This will not only tell you if you are making adjustments that benefit your overclock but will also allow you to easily correct any settings that result in an unstable system. Most BIOS allow you to save your settings as Profiles. Every time you find a successful combination of settings that result in a stable overclock, save them as a profile to make them easier to replicate.
If the boot is successful, run the same benchmark as before and see if the score has improved from your initial score. If the computer fails to restart, or crashes after applying your new CPU Core Ratio settings, go back into BIOS and return to the last known viable settings.
In addition to upping the core ratio, you also may need to modify the voltage being supplied to the CPU if you find that the system isn’t stable after restarting. This setting should be near the CPU Core Ratio settings in your BIOS and is usually called something like CPU voltage or CPU Vcore. Modifying the voltage can help ensure the CPU has the power it needs to run at the higher Core Ratio speeds. Higher frequencies require more power, and that means higher voltages might be necessary.
Read more about voltages and how they can impact your system here.
When raising the CPU core voltage, keep in mind that any additional power running through the CPU will impact its temperature output. It’s important to find the lowest stable voltage in all situations, so only increase your voltage incrementally, by +0.05 V at a time. Then, apply and test until you find a combination of settings that works.
From the BIOS, you are also able to modify built-in safeguards. While adjusting these settings can be beneficial when attempting to overclock, only make changes if you are confident in what you’re doing. The safeguards are there for a reason; altering them improperly can potentially damage your hardware. Learn more about what these safeguards actually do here.
If you find your system is unstable, meaning it won’t turn back on or freezes, check out this section on maintaining system stability for next steps.
After testing, when you’ve achieved the results you’re looking for from your benchmark and you’ve found that your system restarts without issue, move on to the next step.
Step Three: Measuring Performance Gains
To confirm the performance gains from your overclock, run the same benchmark used previously to measure your system’s baseline score. Then compare the results. If the number is improved, you’ve successfully increased the CPU’s performance. From here, you have two options.
- If you are satisfied with the performance gain, you can move on to ensuring system stability.
- If your changes do not result in positive performance gains, go back to the BIOS and continue to adjust your settings until you get the results you are looking for.
Step Four: Stress Test
A benchmark score reflects a system’s measured performance over a short period of time. In order to ensure system stability for longer periods, or for more intensive workloads, it’s important to stress test your CPU’s higher frequency.
There are several stability test software options available. You’ll want to choose the one that most closely mirrors the way you intend to use your system. You can find a sample list here.
After Your Overclock
If you followed the directions above when BIOS overclocking, the results should be a stable system with a CPU that’s running faster than before. If you’ve run your stress test, and the system is stable, you’re done. Congratulations!
It still makes sense to monitor your settings occasionally to make sure your CPU is operating at proper temperatures, especially if you modify or replace any of your other hardware. But most importantly, take the time to enjoy your new overclock and all the benefits a faster CPU can offer.
If you’re ready to get the most of another component, check out our guide on overclocking RAM.