GIGABYTE Z370 Guide to Overclocking Coffee Lake CPUs to 5GHz+

The GIGABYTE OC team prepared a GIGABYTE Z370 overclocking guide for those who wish to get the most out of their Intel Coffee Lake Core i7 and Core i5 processors. The guide was originally published by GIGABYTE and is shared at Overclocking.guide with explicit permission.

Introduction

We’ve been waiting for something awesome from Intel to come out and I think we’re finally onto a winner here. Core i7 in Z-chipset is finally 6 core, 12 thread. Yes!!!! This is the first time after so many chipsets that I feel we finally have a CPU worthy of an upgrade. You know what? That is not the best part yet! Our testing also shows these CPUs are finally capable of 5GHz stable overclock.

Intel’s Core i7-8700K: 5GHz on a 6-core, winning!

Hardware used in this guide

Beginner FAQ

What is overclocking?

Overclocking refers to pushing your computer components harder and faster than the manufacturer designed them to go. CPUs, video cards, and memory often have the capability to run faster than their rated speeds and overclocking takes advantage of that.

Why overclock?

Overclocking your CPU, VGA, and/or memory can result in higher frames per second in games, increase benchmark scores and provide better overall performance of your PC. There are three big reasons to consider overclocking, free performance, reducing FPS dip/stutter and unlocking full performance of high end GPUs.

One of the key areas where overclocking helps gaming is boosting the low/minimum FPS in games. It’s those demanding moments in games with lots of action and textures that can cause a PC to momentarily slow down with FPS dipping to low digits under heavy load where CPU often needs to work very hard and running faster speed will improve FPS and gaming experience. Second important aspect of overclocking is combining a fast CPU with a high end GPU. After high end GPU is bottlenecked games such as PUBG are good examples of this type of behavior and having a fast CPU combined with a decent graphics card will leave you fragging without FPS dips.

Overclocking gives you a free performance boost, why not give it a shot!

Is my notebook processor comparable to my desktop processor?

Desktops have much higher power requirements and better heat dissipation capabilities compared to notebooks. The same model processor in a desktop performs better than the mobile equivalent. CPU speed can have a impact on graphics performance and desktop CPUs will have superior performance because of that.

What can I overclock?

The most often overclocked components are the CPU, video card and memory. In this guide our focus is CPU overclocking.

Disclaimer: Overclock at your own risk!

Overclocking your CPU voids your warranty and it can also damage your CPU, especially if done incorrectly.

How to Overclock Your Intel Coffee Lake i7-8700K & i5-8600K CPUs

For reference we are using a GIGABYTE AORUS Z370 Gaming 7 motherboard and an Intel i7-8700K CPU.

Based on our testing many Intel i7-8700Ks can hit 4.9-5GHz, without delidding, using standard air coolers and around 1.25-1.3Vcore. This is our experience with the CPUs we’ve tested. You may find that your CPU will overclock better (or worse) than our samples so keep that in mind when doing the testing.

 

Step 1: Enter the BIOS by pressing the “delete” button

If you have never been inside your BIOS before, welcome! There is no need to worry, we will guide you step by step with screenshots.

 

Step 2: Load your Extreme Memory Profile (X.M.P.)

Enter “Advanced Frequency Settings”

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Here you see the “Extreme Memory Profile (X.M.P.)” option.
Change it to “Profile 1”. Depending on your RAM you might see a second X.M.P. profile.

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X.M.P. profiles are a quick way to get optimal performance for your memory without having to tweak the settings manually. These settings are verified by the memory manufacturer so you don’t have to worry about stability.

 

Step 3: Change your CPU Multiplier

The formula to calculate the frequency of your CPU is: CPU Base Clock * CPU Clock Ratio.

The Intel i7-8700K the CPU has a Base Clock of 100 and CPU Clock Ratio of 37 for a frequency of 100 * 37 = 3700MHz. In this guide we will be overclocking to 5GHz for a 1300MHz increase.

Set your CPU Clock Ratio to “50”.

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Step 4: Disable Power Management & VT-d settings

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These power management settings may decrease the stability of your system. You can keep them enabled if you think you really need them but we suggest you disable them.

Disable the following power management settings: Intel® Speed Shift Technology, CPU Enhanced Halt (C1E), C3 State Support, C6/C7 State Support, C8 State Support and C10 State Support.

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Step 4: Change Uncore Frequency

The formula for Uncore frequency is CPU Base Clock * Uncore Ratio = Uncore Frequency.

Uncore frequency is the frequency of the non-core parts of the CPU- IE cache, memory controller, etc. To start, set your uncore to 45 and continue on with the guide. After you have determined your CPU’s highest overclock you can re-visit your uncore settings. In general higher uncore values do not produce meaningful performance differences, but they may improve benchmark score.

Set CPU Uncore to “45”.

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*Note: You may find that you lose stability at 5GHz CPU clocks if you raise the uncore frequency really high. Start with uncore at 4GHz and if your system is stable then raise it to 4.5GHz. If you experience instability, try lowering in 100MHz increments.

Under the “Chipset” tab disable VT-d.

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Here you can disable settings or features which may not be necessary in your daily operation. VT-d is used for virtualization. If you don’t plan on using any virtual machines you can disable it. The same stands for the Internal Graphics.

 

Step 5: Adjust Your Voltage Settings

Now that we have set our memory XMP profile, Uncore, and CPU multiplier we must also adjust the CPU voltage (Vcore). In order for the CPU to operate at higher frequencies more voltage will be required.

Go to the starting BIOS page (M.I.T.) and select the “Advanced Voltage Settings” option.

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Select the “Advanced Power Settings” Option

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(Optional) CPU Vcore Loadline Calibration

AORUS Z370 motherboards are already optimized to reduce voltage fluctuation. These voltage fluctuations are built into standard voltage management to reduce power consumption but can also have adverse effects during overclocking as you need a stable fixed voltage to ensure consistency in power delivery. To begin leave LLC on AUTO. If you experience any shutdowns while stress testing set LLC to “Turbo” and test again. If you still experience shutdowns set LLC to “Extreme”. Make sure you also keep an eye out on the CPU load temperature to prevent overheating.

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Step 6: Change CPU Vcore Settings

Go back one page (ESC) or from the main BIOS page (M.I.T) select “Advanced Voltage Control”.

Select “CPU Core Voltage Control”.

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CPU Vcore: Raising this helps keeps the system stable at higher CPU frequencies. However, it also increases the amount of heat your CPU produces. We suggest you keep Vcore under 1.35V depending on your CPU cooling solution. Most CPU’s should be able to overclock to 4.9-5GHz at this voltage, however CPUs are not all created equally. Some may need more voltage, some less.

Set Vcore to “1.28” to start. If you system is not stable raise the voltage in increments of .01 with a maximum of 1.35V.

*Note that changing Vcore voltage also changes your Uncore voltage since they share the same power rail.

 

(Optional) Advanced Settings

The following are settings are optional and might sometimes be needed when overclocking on air or water. There are additional voltages settings not covered here—they are used mostly when trying to hit overclocking records while using liquid nitrogen.

CPU VCCIO and CPU System Agent Voltage: Both of these settings help with DRAM frequency overclocking. Values up to 1.4-1.45V are high but they are ok if you are using aircooling. Since we used X.M.P. profiles for our memory these voltages will be automatically set.

BCLK Adaptive Voltage: This setting helps when you raise the “CPU Base Clock” frequency. You should not need to adjust it because we left “CPU Base Clock” at the default value of 100.

 

Step 6: Save Your Settings

Before rushing off to test your new overclock we suggest saving your profile. You will find this option on the last page of the BIOS named “Save & Exit”.

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Select the option “Save Profiles” and select and name the profile.

Using the “Load Profiles” option you can load the profiles you’ve previously saved. This is very useful when you need to clear the CMOS due to an overly aggressive overclock in which you’ve lost all of your previous settings.

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Step 7: Save & Exit

Last step is to select the “Save & Exit Setup” and click yes on the pop-up window. This will reboot your motherboard and apply all the settings that you have changed.

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Stability Testing

Congratulations! You are now running at 5GHz, which is nothing to scoff at. Now it’s time make sure that it’s stable. We’re going to use the software below to monitor our system, test stability, and adjust our overclocks.

  • Prime95 Version 27.9 Build 1– This is used to stress test our CPU in order to ensure that it’s stable in the most taxing of conditions. This particular version of Prime95 uses AVX instructions which push our CPU to the absolute max.
  • CPU-Z– Used to monitor our CPU frequencies and Vcore settings.
  • CoreTemp– Used to monitor idle, load, and loading temperatures.

 

Step 1: Open up CPU-Z, CoreTemp, and Prime95. Make sure Prime95 is configured. Click the “Small FFTs” preset and then press OK to start.

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Step 2: Start Prime95 and look at “CPU Load” in the CoreTemp app. If one of your cores is not at 100%, your system gets the blue screen of death or just freezes, that means your settings were too aggressive and your CPU has failed the stability test. We normally test for 1 hour. You can keep it running overnight for increased assurance.

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Step 3a (If Prime95 Fails): Close Prime95 by right clicking the Prime95 icon on the tray bar in the lower right side of your screen and selecting “Exit”. This closes Prime95.

 

Step 3b (If Prime95 Fails): Now it’s time adjust your frequency or voltage settings. You can do this either through the BIOS or using EasyTune which is available through the GIGABYTE App Center. You have two options: Either increase CPU Vcore or decrease CPU Clock Ratio. We recommend you to keep CPU Vcore below 1.35 volts if possible. After making an adjustment, go back to Step 1. If it continues to fail dial down your CPU Clock Ratio until you pass stability testing.

 

Step 3C (If Prime95 Fails): If you aren’t stable at 5GHz on Prime95 you can try setting AVX offset to “2”. This will lower your CPU multiplier by 2x when running AVX instruction sets. For instance if your CPU is set go 5GHz it will run at 4.8GHz during Prime95.

 

AVX Offset: AVX Offset ranges from 0 to 31. When you set an AVX offset it will reduce the multiplier by 1-31 (whatever you set it to) when running AVX instruction sets. You can find this setting under “M.I.T” -> “Advanced CPU Core Settings”

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Step 4 (Success): Congratulations, your current overclock is stable. You may want to try for a higher frequency. To do so, experiment with raising your CPU Clock Ratio and CPU Vcore settings either in BIOS or EasyTune and go back to Step 1 to ensure that it’s stable.

Example of a 5GHz non-delidded CPU on air:

 

Delid for Lower Temperatures

There’s an additional way to get extra performance out of your CPU and that is to delid it. Delidding your CPU will reduce your CPU temperatures by 15-20C under load which allows for higher voltage settings thus higher overclocks.

Delidding is the process of removing the integrated heat spreader (silver part) from the PCB (green part). Once you delid you can remove the thermal interface material (TIM) that is used to conduct heat between the IHS and the PCB and replace it with superior performing thermal paste.

There are a few ways to delid. The safest way is to use a delidding tool that is available on the market.

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Thermals

We ran tests using watercooling both delidded and non-delidded Intel Core i7-8700K CPUs to show the difference in thermal performance.

Our Watercooling Setup

  • Water cooler: LEPA AquaChanger 240AIO
  • Motherboard: Z370 AORUS Gaming 7

Non-delidded temperatures in Celsius (average of all cores)

Intel Core i7-8700K 1.28V idle @ 5GHz
Idle ~31.33
Load ~91.83

Delidded temperatures in Celsius (average of all cores)

Intel Core i7-8700K 1.28V idle @ 5GHz 1.32V idle @ 5.1GHz
Idle ~30.16 ~31.16
Load ~85.66 ~90.66

We recommend to always keep an eye on your temperatures and to keep them below 90-95 degrees Celsius.

Results

We’ve increased frequency from 3.7GHz to 5.1GHz—a 1.4GHz increase! The results of our overclocks can be seen in the Intel® Extreme Tuning Utility benchmark below.

Intel Core i7-8700K Default settings Intel Core i7-8700K @ 5GHz Intel Core i7-8700K @ 5.1GHz
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From stock to 5GHz we jump 363 marks from 2204 to 2567. From 5GHz to 5.1GHz we gain an additional 52 Marks.

 

Pushing Past 5GHz

5.1GHz+ is not possible without delidding.  However, delidding voids your warranty. If you do decide to delid your processor, you will increase your chance in obtaining a stable 5.1+GHz overclock. Delidding your CPU will reduce your CPU temperatures by 15-20C under load which allows for higher voltage settings thus higher overclocks.

We recommend using dual-radiator water cooling for the best results. A good air cooler such as the Enermax ETS-T50 or Gigabyte AORUS ATC700 that uses an upgraded push-pull fan setup paired with a good CPU may be able to hit 5.1GHz or higher.

For the specific steps please refer to the overclocking guide above. The specific settings for a 5GHz overclock are listed below.

 

Step 1: Adjust CPU Clock Ratio

Previously we set our CPU Clock Ratio to 50 and now it’s a simple adjustment to 51. Since this overclock is more difficult than the previous 5GHz overclock, we suggest you change these settings through the BIOS.

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Step 2: Adjust CPU Vcore

Since we are aiming for a higher frequency this time, CPU Vcore needs to be increased. Depending on how lucky you were in the CPU lottery the CPU Vcore setting can range from 1.3V to 1.35V. Our particular CPU needed 1.32V to be stable.

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Step 3: Change CPU Vcore Loadline Calibration

In order to reduce any possible Vdroop that interferes with our stability when overclocking set LLC to “Turbo”. If the system is not stable set the LLC to “Extreme”

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Step 4: Stability Testing

Test the stability of these new setting by following the steps under “How to Stability Test”.

Below is an example of a delidded Intel Core i7-8700K using a LEPA AquaChanger 240AIO cooler.

 

AVX Offset: AVX Offset ranges from 0 to 31. When you set an AVX offset it will reduce the multiplier by 0-31 (whatever you set it to) when running AVX instruction sets.

If you aren’t stable at 5.1GHz on Prime95 you can try setting AVX offset to “2”. This will lower your CPU multiplier by 2x. For instance if your CPU is set go 5.1GHz it will run at 4.9GHz during Prime95.

AVX offset is found under M.I.T -> Advanced

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*Note: The processors can be stable at higher frequencies if the load applied doesn’t have AVX extensions. For example this specific CPU is stable at 5.2GHz without AVX load. That means in this case we have 2 options. Either we overclock the CPU at 5.1GHz for all types of loading or we overclock it at 5.2GHz with the AVX option at 2.

 

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Memory Overclocking (X.M.P.)

AORUS Z370 motherboards and the Intel 8th generation processors give us the  opportunity for a slightly better memory compatibility and support.

Below is a short list of what X.M.Ps the AORUS Z370 Gaming 7 supports for now. All the kits have been verified by running Memtest.

Qualified Vendors List (QVL)
DDR4-4133
Module Supplier Density Module P/N. BIOS:F3C
4 DIMM
CORSAIR 8GB CMK32GX4M4E4133C19R v4.31 Normal
DDR4-4000
Module Supplier Density Module P/N. BIOS:F3C
4 DIMM
CORSAIR 8GB CMK32GX4M4B4000C19R v4.31 Normal
G.SKILL 8GB F4-4000C18Q-32GTZ Normal
DDR4-4000
Module Supplier Density Module P/N. BIOS:F3C
2 DIMM
CORSAIR 8GB CMK32GX4M4B4000C19R v4.31 Normal
CORSAIR 8GB CMK16GX4M2B4000C19R v4.31 Normal
G.SKILL 8GB F4-4000C18Q-32GTZ Normal
DDR4-4000
Module Supplier Density Module P/N. BIOS:F3C
2 DIMM
CORSAIR 4GB CMK8GX4M2B4000C19R Normal
CORSAIR 4GB CMK8GX4M2B4000C19 Normal

Here’s an example of Aida64 with just the 4133MHz XMP enabled using a 4x8GB(32GB) memory kit.

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Combining the 5G profile from above and the 4133MHz X.M.P. we get the following results.

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The results stand out in the following table:

Aida64 Stock settings 4133MHz X.M.P. i7 8700K @ 5GHz, 4133MHz X.M.P.
Read 32963 MB/s 52269 MB/s 55243 MB/s
Write 33455 MB/s 62616 MB/s 62832 MB/s
Copy 31732 MB/s 52177 MB/s 53492 MB/s

This chipset and board are strong memory overclockers. We can easily run AVX instructions combined with 4133MHz X.M.P. with all the DIMM slots populated while running prime95! Here’s an overnight run passing prime95:

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For a shorter period of time 5.1GHz with 4133MHz is also possible.
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