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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: Best CPUs

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 Clock
Core i9-9900KS4.0 GHz5.0 GHz5.0 GHz
Core i9-9900K3.6 GHz5.0 GHz4.7 GHz
Core i7-9700K3.6 GHz4.9 GHz4.6 GHz
Core i5-9600K3.7 GHz4.6 GHz4.3 GHz
Core 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.

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. 

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 Maximum
Operating VoltageN/A1.52V1.40V
VCCIO0.95VN/A1.30V
VCCSA1.05V1.52V1.30V
  • Gurg
    Curious why you don't use Intel Extreme Tuning Utility to set your overclock and then the included stress test rather than going through the bios and using non-Intel tests? I've gone the bios route before and its more of a pain to continually tinker with changing the rates by restarting to get to the bios. Once I set my overclock I like occasionally leaving the Intel Extreme system monitor screen open while running benchmarks to see how my PC is running. My 9600K runs at 5.05 all-core. I left my core and cache voltages in the adaptive mode rather than setting a value.
    Reply
  • Unolocogringo
    Gurg said:
    Curious why you don't use Intel Extreme Tuning Utility to set your overclock and then the included stress test rather than going through the bios and using non-Intel tests? I've gone the bios route before and its more of a pain to continually tinker with changing the rates by restarting to get to the bios. Once I set my overclock I like occasionally leaving the Intel Extreme system monitor screen open while running benchmarks to see how my PC is running. My 9600K runs at 5.05 all-core. I left my core and cache voltages in the adaptive mode rather than setting a value.
    I'm not the author of this simple piece of information, but I can answer your question.
    Almost all overclocking software produces terrible overclocks from an experienced overclocker"s point of view.
    Many are just plain unstable at the software's setting.
    Almost all apply too much voltage, which is counterproductive for really high desktop overclocks.
    Their 10,15,30 minute stress tests are a joke for true stability testing.
    Most software overclocks are unstable and will slowly corrupt the hard drive over time.

    If he/she had suggested using software overclocking he would of lost all credibility as a author and most comments would be complaints.
    Most serious overclocking enthusiast would call him/her out for giving bad advice.
    Reply
  • mdd1963
    None of the above list of alleged grievous 'software-overclocker deadly sins' listed above remotely or even applies to Intel's XTU, ergo, listing what alleged issues some other software OC sources (assorted OC Genies/Masters, etc) had or might have caused some 10-15 years ago seems ... irrelevant, at best.

    Too high a voltage at default? - a core voltage value or offset, either plus or minus, is/can be applied within XTU, identically as if it had been set in the BIOS; ergo there is no default voltage increase or decrease applied. (THis fault would actually readily apply to any BIOS within any mainboard manufacturer, but, can be quickly overridden within the XTU)

    The ability to manipulate base clock speed of 100 MHz is there, but, I don't know many that advocate this on today's mainboards.

    The normal Intel power limits may also be tweaked here, as well as applying AVX offsets. and desired clockspeed/multiplier values entered for specific number of cores active. User may adjust Turbo Boost features (on/off, short boost power max, max power enable, boost duration, etc) a lower cache clock speed may be specified if desired.
    stress Test - although the XTU does include both CPU/RAM stress test options (which have fluctuating workloads that induce temperature peaks approximately equal to those of CPU-Z's included stress routines), those are to be run manually, and are not used in some 'auto-tuning'/stability test. No one included test is really a test of stability anyway, as what good does it do to pass Prime 95/small FFTs, but, fail in CInebench/Blender, or hard reset in gaming, etc..? With SpeedStep still enabled and Balanced still selected in power plans, the rig still turbos to the high specified maximums, but, downclocks to 800-1200 MHz when loafing at the desktop, etc..

    Last but not least, an XTU config file is referenced/accessed very early in each bootup; if the file was not accessed/correctly appended during a clean shutdown, all values manipulated in XTU are set aside/returned to default, quite useful if one has overstepped the bounds of stability in the search for that last 100 MHz, etc...

    Intel's XTU has been a delight to work with, a very quick way to access ~90% of what most folks tweak in the BIOS. Are there a few more options in the BIOS? Of course.
    Reply
  • jpe1701
    Just a note to the author. In the paragraph talking about setting voltage you say it won't hurt to add more volts. You should word it a little differently I think so that it's not taken literally. Lol
    Reply
  • Deicidium369
    AMD Overclocking Guide - long version

    You can not overclock an AMD CPU - AMD already overclocked it.
    ==
    AMD Overclocking Guide - short version

    You can't.
    Reply
  • Unolocogringo
    mdd1963 said:
    None of the above list of alleged grievous 'software-overclocker deadly sins' listed above remotely or even applies to Intel's XTU, ergo, listing what alleged issues some other software OC sources (assorted OC Genies/Masters, etc) had or might have caused some 10-15 years ago seems ... irrelevant, at best.

    Too high a voltage at default? - a core voltage value or offset, either plus or minus, is/can be applied within XTU, identically as if it had been set in the BIOS; ergo there is no default voltage increase or decrease applied. (THis fault would actually readily apply to any BIOS within any mainboard manufacturer, but, can be quickly overridden within the XTU)

    The ability to manipulate base clock speed of 100 MHz is there, but, I don't know many that advocate this on today's mainboards.

    The normal Intel power limits may also be tweaked here, as well as applying AVX offsets. and desired clockspeed/multiplier values entered for specific number of cores active. User may adjust Turbo Boost features (on/off, short boost power max, max power enable, boost duration, etc) a lower cache clock speed may be specified if desired.
    stress Test - although the XTU does include both CPU/RAM stress test options (which have fluctuating workloads that induce temperature peaks approximately equal to those of CPU-Z's included stress routines), those are to be run manually, and are not used in some 'auto-tuning'/stability test. No one included test is really a test of stability anyway, as what good does it do to pass Prime 95/small FFTs, but, fail in CInebench/Blender, or hard reset in gaming, etc..? With SpeedStep still enabled and Balanced still selected in power plans, the rig still turbos to the high specified maximums, but, downclocks to 800-1200 MHz when loafing at the desktop, etc..

    Last but not least, an XTU config file is referenced/accessed very early in each bootup; if the file was not accessed/correctly appended during a clean shutdown, all values manipulated in XTU are set aside/returned to default, quite useful if one has overstepped the bounds of stability in the search for that last 100 MHz, etc...

    Intel's XTU has been a delight to work with, a very quick way to access ~90% of what most folks tweak in the BIOS. Are there a few more options in the BIOS? Of course.
    Their are still lots of overclocking software available today.
    Most published by motherboard makers themselves.Built into the bios and software for windows. Not 10-15 years old.
    Brand new in boxes waiting to be purchased.
    Those of us who must have 100% stability can not rely on them. My folding comruters are overclocked to stability limits and run 3 months between reboots.
    I install updates. shut down for cleaning. take them outside and blow them out with an air compressor. Bring it back in and fire it back up for another 3 months.
    They run almost 100% load for three months and repeat.

    Never used XTU but it sounds like most other overclocking software that has a manual mode or an automatic OC mode.
    Never had good luck with any of them so manual it is for me.Gave up on trying software and went back to bios overclocking many years ago.
    Other people might want to learn how and this is a decent beginners guide.

    Otherwise it would be a very short article.
    start overclocking software.
    press start.
    put check mark in box to start with windows.
    press accept.
    done.
    end of article.
    If the article title was "how to overclock with XTU" that would be different.
    Reply
  • mamasan2000
    Number 1 rule when it comes to overclocking: Every silicon is different. Don't you think Intel built the software with that in my mind? There is variation in OC you can reach and therefor Intel probably went with the safer bet, lower clocks and voltage.
    They don't want support tickets or returned CPUs, that hurts the bottomline.
    You are leaving perf on the table. If you are going to OC, do it right. Manually. Test with multiple tests. If any of them crash, it is not stable.

    If you are going to overclock, learn what each setting does.

    And if you've noticed, none of the professional overclockers are out of a job. That should tell you something.
    Software is not the way to go for OC. No one half-serious uses it.
    Reply
  • Gurg
    mamasan2000 said:
    Number 1 rule when it comes to overclocking: Every silicon is different. Don't you think Intel built the software with that in my mind? There is variation in OC you can reach and therefor Intel probably went with the safer bet, lower clocks and voltage.
    They don't want support tickets or returned CPUs, that hurts the bottomline.
    You are leaving perf on the table. If you are going to OC, do it right. Manually. Test with multiple tests. If any of them crash, it is not stable.

    If you are going to overclock, learn what each setting does.

    And if you've noticed, none of the professional overclockers are out of a job. That should tell you something.
    Software is not the way to go for OC. No one half-serious uses it.
    Intel XTU overclocks the cpu in steps until it fails so as to find the highest possible overclock. Mine would do 5.0 fine, but not 5.1. When I used the advanced tuning I set it to run at 5.0 and so it does all day at max temps generally in seventies. When I tried 5.1 it failed. When reviewers overclock 9600K, most everyone gets to 5.0. I saw just one that made 5.2 and one that could only get 4.9.

    TH: "We tapped Corsair's H115i v2 to test our Core i5-9600K, which gave us enough headroom to run at 5 GHz with 1.36V Vcore and Auto Load Line Calibration settings. An AVX offset wasn't needed; our sample maintained ~80°C during AVX workloads. The temperature only reached ~64°C during non-AVX workloads. Although some Core i5-9600K CPUs reportedly run stable at up to 5.2 GHz, we aren't comfortable pushing our chip beyond the "safe" 1.35V limit."

    Time Spy Advanced which allows you to search by CPU and GPU shows a handful of 9600K that evidently won the silicon and probably the Z390 motherboard lottery at 5.3. The motherboard factors in because when I tried to double my memory to 32gb with the same identical RAM my system would not run at same settings as before. It shouldn't be my PSU as it is a 1000 watt PSU. I admit I only went with a $120 Z390.
    Reply
  • PCWarrior
    With regards to XTU, it does have direct control of BIOS settings –in other words you can directly modify the BIOS settings. It is not a mere software overclock applied at windows startup like the various gpu software OCing tools such as the MSI afterburner. You do not need to run XTU each time you boot your computer. That being said it depends on the motherboard manufacturer or OEM to expose these BIOS controls to XTU. All DIY desktop boards from the big 4 (ASUS, Gigabyte, MSI, ASRock) do so. For OEMs and laptops where they may not expose these controls, XTU can act like traditional software OC tools. Also, some people seem to confuse XTU with auto-overclocking tools like the Intel Performance Maximiser or ASUS’ AI overlocking tool.
    Reply
  • PCWarrior
    My Overclocking stress testing procedure

    Phase 1
    For a quick stability test I use 3-5 consecutive runs of Cinebench R15 and/or Cinebench R20. If the system is unstable it will be revealed though this method about 90-95% of the time. I also check whether the score has increased nearly linearly with the frequency – if it does not it is almost always a sign of an underlying instability. At this stage I perform the tests with fixed voltage. Once I find an overclock that is stable and with predicted score increase in Cinebench I switch to adaptive voltage and rerun the tests.

    Phase 2If phase 1 is successful I pass to the second phase of testing the system further.
    I first perform a thermal test to check what are the worst-case, steady-state temps and see if my cooling solution is adequate. For that I use the IntelBurnTest and small FFT prime 95 for 15-20 minutes each. These tests will absolutely pummel the cpu and produce maximum heat and highest temps. Best way to monitor temps and power is HWinfo and Intel’s XTU. The latter also shows you whether the cpu is throttling.
    If I am happy with the temps, I move to further test stability. Intel’s XTU benchmark for starters followed by running the build-in stress tests (CPU and memory) for 15minutes each.
    Then Realbench as it also includes Blender. I do a couple of runs.
    Then I test with OCCT were I can I set a temperature limit for the stress test (e.g. 84C) above which the test is automatically terminated. I test for 1hour with the OCCT test and for another 30minutes-45minutes with the Linpack including full memory test.
    Then I test with the 3D Mark Time Spy by running the benchmark a couple of times followed by a couple of runs of Fire Strike and Fire Strike Extreme. When I run the benchmarks, I look (obviously for crushing but also) for any signs of stuttering and whether there is the expected score increase in the cpu score with the increase in frequency.
    Subsequently I use Memtest64 for almost the entire RAM capacity (e.g. 30.5GB for 32GB of installed RAM). I do 3-4 full passes.
    As a final confirmation I may run Prime95 for 4-5 hours, but I find this practice unnecessary as it never produces any error after all the previous stages had successfully passed.
    Just to guarantee 100% stability, especially if I am aiming for my “mild 365/24/7 Overclock” I may sometimes decide to dial back 100MHz while keeping the voltage the same or set an AVX offset.Phase 3The third phase is to try to do per-core overclocking and try to basically ‘rewrite’ Intel’s turbo 2.0 table with higher frequencies. You can do this easily through XTU but I prefer to do it the old fashioned way through the BIOS. So, for example, for an i9 9900K, if my all-core OCed turbo was 4.9GHz I would try:

    1-2 active cores - 5.2GHz
    3-4 active cores - 5.1GHz
    5-6 active cores - 5.0GHz
    7-8 active cores - 4.9GHz

    Then repeat phase 1 and 2 above all over again…

    Phase 4Then I just use the PC but I keep looking for possible odd behaviour while using various intensive apps or games.
    Reply