Overclocking Intel processors used to be a very complicated manual process that found enthusiasts knee-deep in the BIOS, sifting through a myriad of complicated settings. Nowadays, motherboard manufacturers have created automatic overclocking software and one-button predefined presets in the BIOS that can greatly simplify the process of extracting the utmost performance from one of the Best CPUs for gaming, but that isn’t always the best option.
Simplified alternatives can produce satisfactory Intel overclocks, but they often apply an unnecessary amount of voltage and generate excess heat, so there’s always room for improvement. More often than not, you could achieve better results by taking the time to manually overclock your Intel CPU instead of having a piece of software do it for you. Furthermore, you also get to learn more about your system, and, as they say, knowledge is power.
As always, we have to remind you that there are risks involved with overclocking. First, you’re voiding the warranty whenever you run an Intel processor outside of the manufacturer’s specifications. In addition, there’s always a possibility of premature failure if you overclock a CPU incorrectly. Finally, you’re at the whims of the silicon lottery — not every chip can achieve the same overclocks.
Nevertheless, today’s modern chips have a plethora of in-built safety mechanisms that help reduce the risks associated with overclocking. As a result, if you take a common-sense and responsible approach, you can squeeze every single megahertz out of the processor without assuming unnecessary risks. Here’s how.
Do I own an overclockable processor?
Intel designates its overclockable CPU models with the “K” suffix. These overclockable models land in the Core i9, i7, i5, and occasionally, i3 families. And, of course, there are the KF-series (overclockable and graphics-less) models. Intel has also released special-edition models like the Core i9-9900KS that support overclocking, but those have become rare.
Does my motherboard allow me to overclock?
Intel chipsets with the “Z” suffix are the only models that fully support overclocking all of the tunable parameters.
In addition, Intel also now allows memory overclocking on locked SKUs compatible with B560 and H570 chipsets, meaning all 10th-Gen Comet Lake, 11th-Gen Rocket Lake, and 11th-Gen Comet Lake Refresh processors. We also expect those policies to apply to 12th-Gen chips and 600-series motherboards. However, you still cannot overclock core frequencies on locked models.
The second important aspect of the motherboard is the power delivery subsystem that’s commonly known as the voltage regulator module (VRM). If you’re not sure of the quality of the VRMs on your motherboard, our list of the Best Motherboards is a great place to start. There you can find the best models for overclocking and links to more resources, like our in-depth motherboard reviews and guides.
Can my CPU cooler keep my overclocked processor cool?
Never overclock on a stock cooler. In fact, it’s a blessing that Intel stopped including stock coolers with the brand’s K-series chips — that way, users don’t fall to the temptation of overclocking their chips with these largely useless chunks of aluminum.
Both aftermarket air and liquid coolers are good at what they do and can provide you with some overclocking headroom. However, cooling is one of the biggest limiting factors to your overclock, so you’ll need to right-size your cooling solution to your chip. In addition, other factors, like budget, clearance space inside your case, and personal preference, will influence your choice of cooler. If you feel your CPU cooler isn’t up to the task, we’ve detailed what we consider the best air and liquid coolers in our Best CPU Coolers 2021: Air and Liquid article.
Does my power supply have sufficient headroom?
It’s important to evaluate your power supply’s capacity to see whether it has the necessary headroom to accommodate the increased power draw. An underpowered power supply might lead to unwanted system shutdowns, restarts, or, in a worst-case scenario, the power supply could die and take a few of your components with it.
For context, our tests show that modern overclocked CPUs can pull more than 320W of power after overclocking. Therefore, we recommend that your power supply has at least 150W to 250W of headroom over what’s required for stock operation. You can see the basic guidelines with a power supply calculator, then head to our list of Best Power Supplies to assure that you have an adequate unit for your system.
Get To Know Your Motherboard
No two motherboards are the same, and motherboard makers tend to overcomplicate things by using different terminologies for the same settings. Luckily, most brands include a short description for each option inside the BIOS, so you shouldn’t have any problems finding the equivalent term for your motherboard. You can also use software-based utilities that use the same terminology regardless of the motherboard.
There are a plethora of settings and voltages that you can play with that affect your processor both directly and indirectly. For the scope of this article, we’ll only focus on the basic settings that you’ll need to get your overclock up and running.
- Base Clock (BCLK) – The frequency at which the processor communicates with the memory and PCIe devices. The default BCLK for Intel chips is 100 MHz, but you can adjust this for smaller incremental performance increases. However, be aware that adjusting the base clock also impacts the PCIe and memory busses. As such, you should refrain from adjusting your BCLK until your overclock is stable. Even then, it would be best if you did so sparingly.
- CPU Multiplier – Dictates the ratio between the CPU and the BCLK. The formula to determine the processor’s frequency consists of multiplying the base clock by the CPU multiplier. For example, a processor with a 100 MHz BCLK with a multiplier of 40 will operate at 4,000 MHz, or 4 GHz.
- CPU Core Ratio – Lets you choose whether you want to set the multiplier for all the cores in a group, or individually. The latter is referred to as per-core overclocking, and it allows you to tune individual cores to their highest potential instead of the lowest common denominator. This approach can also allow you to squeeze at least some overclocking headroom out of systems with lesser coolers.
- Vcore – This voltage goes by many names, like Core Voltage or vCore, but it always represents the motherboard’s main input voltage to the processor. This value has the most direct input on thermals, with higher amounts of voltage generating more heat.
- Voltage Mode – Auto lets the motherboard decide the voltage to apply to the processor while ‘Manual’ or ‘Override’ allows you to assign a fixed Vcore. Offset mode adds a specific amount of voltage to the processor regardless of the frequency, while Adaptive voltage increases the voltage when the processor operates in turbo mode.
- AVX Offset – A separate multiplier that can adjust the processor frequency when it executes AVX workloads. AVX instructions yield massive speed-ups, but these instructions also generate more heat and consume more power than other types of instructions, which can lead to system instability during overclocking. Most garden-variety software and games do not use AVX instructions, so dialing the AVX offset back to reduce the core frequency during these taxing workloads is critical to attaining peak performance in non-AVX applications.
- Load-Line Calibration (LLC) – Sometimes, typically when the processor is first placed under load, the CPU doesn’t receive the amount of voltage set by the user. This condition is caused by voltage droop (Vdroop) and it can result in either lower or higher voltages than intended. Load-line calibration basically compensates for Vdroop by assuring that voltages remain on an even keel. There are multiple LLC options in most motherboards, but Auto typically suffices for most users with higher-end (or newer) motherboards.
- Intel SpeedStep – Feature that increases or decreases processor speed and voltage according to system load.
- Uncore – Regulates the frequency of the different controllers on the processor like the L3 cache, ring bus, memory controller, etc.
- FCLK – Controls the speed at which data is passed from the processor to the graphics card.
- VCCSA – Voltage for the System Agent. Increasing this voltage can help stability when overclocking the ring bus and cache frequency.
- VCCIO – Voltage for the memory controller and shared cache.
- Extreme Memory Profile (XMP) – Enables the XMP profile on compatible memory kits. XMP profiles apply pre-validated memory overclocks by simply toggling the feature on in either the BIOS or a software overclocking utility.
How to Overclock
Before you begin overclocking, always be sure to establish baseline measurements of both performance and CPU thermals. This will allow for an easy comparison of how much impact an overclock has on both CPU heat and performance. Overclocking can be a balancing act that requires a few compromises. This data helps you gauge the acceptable tradeoffs for the amount of performance you gain.
1. Enter the BIOS or open software overclocking utility. Our tutorial on accessing the BIOS explains how, but for most desktop PCs, hitting the Del key on your keyboard as soon as you see the motherboard logo pop up on your monitor works. You can also use a software-based overclocking utility, like Intel XTU, to adjust many of the same parameters.
2. Set the CPU multiplier to your desired overclock. You can choose to apply an ‘all-core’ overclock, meaning that all cores will operate at the same frequency, or on newer Intel processors, assign different frequencies for individual cores. You can also overclock via the ‘Turbo Ratio,’ which allows the CPU to boost to different overclocked frequencies based on the number of active cores.
There are two various approaches to this step — You can gradually increase your processor’s frequency using 100 MHz increments until you’ve hit the wall, or you can set the desired frequency and work your way up or down from there.
3. Adjust CPU Voltage (Vcore). We suggest starting with a low Vcore (1.25V or lower) as the starting point and then working your way up if your system isn’t stable at your desired frequency. Maximum voltage thresholds vary based on the generation of the Intel processor you’re overclocking. However, a general rule of thumb is not to exceed 1.40V for 9th-Gen and newer processors unless you’re using exotic (sub-ambient) cooling. Higher voltages will result in faster chip degradation.
There is no magic formula when it comes to overclocking. If you want to pinpoint the exact voltage for stability, use small increments of 0.01V. If you’re not the patient type, you can work with higher increments, like 0.05V.
Be aware that temperatures will rise, and frequency improvements will decline, on a non-linear basis with voltage increases. That means you’ll get less of a return in exchange for more heat as you work your way up the voltage scale. We suggest not using the borderline voltage for stability. Overclocking isn’t a precise science, and hardware is unpredictable.
4. Configure the voltage mode to the selection of your choice. We suggest using a static (override) voltage mode until you’ve dialed in your overclock. After that, you can try other modes. Adaptive mode is often popular because the Vcore decreases with the multiplier, which will make the processor generate less heat and consume less power.
5. Set the AVX offset to -1 or -2 to reduce the multiplier when your processor engages in AVX workloads. AVX workloads hit the processor hard and, as a result, require more voltage to achieve stability. It isn’t uncommon to see high overclocks accompanied by -3 or -4 offsets.
6. Set the LLC. Some motherboard brands prefer to use numeric values to determine the LLC level while others use non-numeric values. For the average user, a medium value should be more than enough. You can experiment with the different values to see which works best for you, though.
Newer-generation motherboards, particularly higher-end models, tend to adjust this setting automatically with precision. Unless you’re chasing the highest of overclocks, you can often leave this setting unaltered.
7. Set Intel SpeedStep to enabled or disabled. It’s your call if you want your processor to always run at the overclocked frequency, or downlock when it’s idle. If you leave SpeedStep enabled, be aware that the ‘High Performance’ Windows power plan will not allow the processor to downclock during idle periods. You’ll need to use ‘Balanced’ or a lesser power plan to enable downclocking.
8. Boot your system to see if it starts. If the system is unstable, continue tweaking the Vcore until you find stability. Cycle through the stability tests below to find your maximum core overclocks.
9. Enable XMP to automatically set up your memory modules to run at their advertised speed. If you’re running faster memory, make sure your system is stable before overclocking the memory. You want to avoid guessing if future system instability is caused by the memory overclock or the processor overclock.
Software For Testing Stability And Monitoring
There are a lot of free programs that help you test your overclocked processor’s stability. It’s probably best to use a tandem of programs since each stresses the processor differently. At the end of the day, these programs are designed to hit the processor very hard, so it’s important to always keep your eye on the processor’s temperature during the tests. Most K-series processors start throttling at 100C, which means they will lower clock speeds and voltages to avoid thermal damage. You want to avoid hitting this threshold during your testing. Also, adjusting only one parameter between stress test attempts will greatly simplify the process.
Ideally, you want to keep temperatures below 80-85C degrees Celsius (C) under load for everyday operation. You also do not want to exceed 30C during idle. Both of these basic guidelines will help reduce the impact of chip degradation. If the chip wears enough, it triggers electromigration (the process of electrons slipping through the electrical pathways), which leads to premature chip death. Some factors are known to increase the rate of wear, such as the higher current and thermal density resulting from overclocking.
Electromigration doesn’t occur overnight, and most chips live long past their warrantied lifespan even under heavy overclocks, but you are assuming somewhat of an undefined risk. Using Turbo Ratio-based overclocking techniques tends to be safest, as it reduces the amount of time the processor is exposed to degradation-causing conditions.
Stress tests are a good way to evaluate your overclock’s stability. Some hardcore enthusiasts love frying their chips for days at a time to ensure stability, while others do just a few hours of stress testing and call it a day. It’s up to you to decide how long you want to run the tests. Just don’t fixate on them, and throw some daily usage into the mix as well. Also, be sure to watch for signs of instability that are more subtle than an outright BSOD. For example, consider the system unstable if it hitches, stutters, or has momentary freezes.
Passing Prime95 doesn’t necessarily mean your processor is stable for other workloads, either. Remember, you can only prove instability, not stability. This means that regardless of the length of time that you stress test your processor and pass, you can still encounter a random BSOD. As such, don’t overclock mission-critical systems. You can reference our How to Stress-Test CPUs and PCs (Like We Do) article for more detail.
CPU-Z is the de facto program for monitoring your processor’s frequency. AIDA64 and HWiNFO64 are also popular choices. Take into consideration that you should only run one monitoring program at a time. Running two or more simultaneously is counterproductive and causes polling issues. You could end up with inaccurate readings.
If your overclocked system is unstable when you activate XMP, it might be necessary to tweak the VCCIO and VCCSA voltages. These two voltages are helpful when you want to stabilize a memory overclock. Be warned, though, VCCIO and VCCSA are sensitive voltages, meaning too much can be equally detrimental as not enough. It would be best to tweak the voltages with small increments of 0.01V until your memory overclock is stable.
For reference, the default voltages for VCCIO and VCCSA on Coffee Lake processors are 0.95V and 1.05V. Intel doesn’t list a maximum safe voltage for the first, but the latter is 1.52V. For the well-being of your processor, don’t exceed 1.30V on either voltage.
There is some value to overclocking the uncore, but you’ll see the biggest performance gains from overclocking the core. Therefore, you should always prioritize higher core speeds over the uncore. We recommend you only play with the uncore once you’ve dialed in your maximum core overclock. Start with an uncore multiplier that’s three to four times lower than your processor’s all-core boost multiplier and work your way up.
Increasing the FCLK can net you a small improvement if you’re using a discrete graphics card.