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How to Overclock an Intel CPU: Get the Most MHz from Your Processor

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Overclocking Intel processors used to be a very complicated process. Nowadays, motherboard manufacturers have created automatic overclocking software and one-button predefined presets in the BIOS. While both alternatives produce satisfactory Intel overclocks, they are not perfect and there is always room to improve. 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.

Whenever you run an Intel processor outside of the manufacturer’s specifications, you’re voiding the warranty. In addition, there’s always a possibility of premature failure if you overclock an Intel CPU incorrectly. Nevertheless, if you approach overclocking an Intel CPU responsibly, you can squeeze every single megahertz out of the processor.


MORE: Intel & AMD Processor Hierarchy

Overclocking Checklist

Do I own an overclockable processor?

Intel designates the overclockable models with the “K” suffix. With the Coffee Lake family, you have the Core i9-9900K, Core i7-9700K, Core i5-9600K and Core i3-9350K. And, of course, there are the F-series (graphics-less) counterparts to the aforementioned SKUs and the special-edition Core i9-9900KS that also support overclocking.

Does my motherboard allow me to overclock?

Intel chipsets with the “Z” suffix are the only ones that enable overclocking. The second important aspect with 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 VRM on your motherboard, reviews are a great place to start.

Can my CPU cooler keep my overclocked processor cool?

Never overclock on a stock cooler. It’s a blessing that Intel stopped including stock coolers with the brand’s K-series chips so users don’t fall to the temptation to overclock their chips with these pieces of copper. Both aftermarket air and liquid coolers are good at what they do. It just comes down to budget, clearance space inside your case and personal preference. If you feel that 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 2020: 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 and restarts or, in a worst case scenario, the power supply dies and takes a few of your components with it.

For context, our tests show that the Core i9-9900K can pull up to 200W of power at stock settings. When overclocked to 5 GHz, the power consumption increased by 50W. Therefore, we recommend you have at least 150W to 250W of headroom in your power supply before you go on your Intel overclocking adventure. There are online power supply calculators that estimate the power draw for you or you can get a Kill-A-Watt meter to measure it yourself.

Peace Of Mind For $20

Intel introduced the Performance Tuning Protection Plan (PTPP) so enthusiasts can overclock with a certain level of tranquillity.The Performance Tuning Protection Plan basically covers processor failures due to overclocking.

Generally, you can purchase most protection plans directly from Intel for $19.99 but some are more expensive based upon the price of the processor. We think it’s a reasonable price to pay to protect your hard-earned investment. Aside from the Core i3-9350K, almost all the Coffee Lake K-series parts are eligible for the Performance Tuning Protection Plan.

Get To Know Your Motherboard

No two motherboards are the same. Brands tend to overcomplicate things for the end user by using different terminologies for the same thing. Most brands include a short description for each option inside the BIOS. You should have no problem finding the equivalent term for your motherboard. There are a plethora of settings and voltages that you can play with that directly and indirectly affect your processor. For the scope of this article, we’ll only be focusing on basic settings 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 Coffee Lake chips is 100 MHz.

CPU Multiplier – Dictates the ratio between the CPU and the front-side bus (FSB). The formula for determining 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.

Vcore – The voltage the motherboard provides to the processor.

Voltage Mode – Auto lets the motherboard decide. Manual sets a fixed Vcore. Offset mode adds a specific amount of voltage to the processor regardless of the frequency. Adaptive voltage only increases the voltage when the processor is operating in turbo mode.

AVX Offset – A separate multiplier to downlock the processor when it’s executing AVX workloads

Load-Line Calibration (LLC) – Sometimes, typically when the processor is under load, it doesn’t receive the amount of voltage set by the user. The problem is called Vdroop, which stands for voltage droop. Load-line calibration basically compensates Vdroop by providing extra voltage.

Intel Speedstep – Feature that increases or decreases processor speed and voltage according to the load.

Uncore – Regulates the frequency of the different controllers on the processor like the L3 cache, memory controller, etc.

FCLK – Controls the speed in which data is passed from the processor to the graphics card. By default, Coffee Lake has an 800 MHz FCLK.

VCCSA – Voltage for the System Agent.

VCCIO – Voltage for the memory controller and shared cache.

Extreme Memory Profile (XMP) – Enables the XMP profile on compatible memory kits.

How to Overclock

1. Enter the BIOS. 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.

2. Enable XMP to automatically setup your memory modules to run at their advertised speed. The official support memory on Coffee Lake is DDR4-2666. If you’re running faster memory, make sure your system is stable before overclocking the processor. You want to avoid guessing if future system instability is caused by the memory overclock or the processor overclock.

3. Set the CPU multiplier to your desired overclock. There are two different 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 a desired frequency and work your way up or down from there.

Intel markets the single-core boost clock speed for its processors. We’ve listed the all-core boost clock speeds for the various Coffee Lake K-series chips for your convenience.

4. For the CPU core ratio, choose the option to synchronize all cores so that you overclock all the processor’s core to the same frequency.

5. We suggest using a 1.25V for the Vcore as the starting point. Intel details the maximum voltages for Coffee Lake processors in this document and recommends a maximum operating voltage of 1.52V. The value is just insane for daily usage, and there’s zero possibility of cooling a processor at that voltage without resorting to exotic cooling. For safe measure, keep it below 1.40V.

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.

We suggest not using the borderline voltage for stability. Overclocking isn’t a precise science, and hardware is unpredictable. It doesn’t hurt to add a couple of volts to your borderline voltage for some headroom.

6. Configure the voltage mode to the selection of your choice. We suggest adaptive mode because the Vcore decreases with the multiplier, which will make the processor generate less heat and consume less power. It also increases processor longevity.

7. 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.

8. 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

9. 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.

10. Boot your system to see if it starts. If the system is unstable, continue tweaking the Vcore until you find stability.

ModelBase ClockSingle-Core Boost ClockAll-Core Boost ClockCore i9-9900KS4.0 GHz5.0 GHz5.0 GHzCore i9-9900K3.6 GHz5.0 GHz4.7 GHzCore i7-9700K3.6 GHz4.9 GHz4.6 GHzCore i5-9600K3.7 GHz4.6 GHz4.3 GHzCore i3-9350K4.0 GHz4.6 GHz4.4 GHz

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. Ideally, you would want to keep temperatures below the 85 degrees Celsius (C) for everyday operation. Coffee Lake K-series processors start throttling at 100C.

Stress tests are a good way to evaluate your overclock’s stability. There are hardcore enthusiasts that love frying their chips for days at a time to ensure stability, and others that 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. Passing Prime95 doesn’t necessarily mean your processor is stable for other workloads, either.

Prime95Intel Burn TestAIDA64HandBrakeROG RealBench

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.

HWMonitorAIDA64HWiNFO64Core TempReal Temp

Overclocking Appendix

Memory Overclocking

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.

Uncore Overclocking

There is some value to overclocking the uncore, but you’ll see the biggest performance gains from overclocking the core. In most situations, the uplift for a higher uncore is negligible. 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. The real good samples can run the uncore at the same frequency as the core. Take note that the uncore voltage is tied to the Vcore so the only way to achieve a high uncore is upping the voltage, but it’s not worth increasing the Vcore just to get a higher uncore.

FCLK Overclocking

Increasing the FCLK can net you a small improvement if you’re using a discrete graphics card. The default FCLK for Coffee Lake is 800 MHz. You can set the multiplier to x10 for 1,000 MHz.

Coffee Lake Voltage Cheat Sheet VoltagesIntel DefaultIntel MaximumRecommended MaximumOperating VoltageN/A1.52V1.40VVCCIO0.95VN/A1.30VVCCSA1.05V1.52V1.30V



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