GIGABYTE X299 Skylake-X Overclocking Guide

The GIGABYTE OC team prepared a GIGABYTE X299 Skylake-X overclocking guide for those who wish to get the most out of their Intel Skylake-X Core i7 and Core i9 processors. The guide was originally published by GIGABYTE and is shared at with explicit permission.


GIGABYTE X299 Skylake-X Introduction

Single Threaded & Multi threaded performance

Previous to Skylake-X users had to choose between single-threaded and multi-threaded performance. A choice between more cores and higher clocks. With this OC guide you will be able to push your Skylake-X to match performance in single-threaded applications and dominate in multi-threaded workloads.


GIGABYTE X299 Skylake-X OC 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.

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.

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 i9-7900X CPU

For reference we are using a GIGABYTE AORUS X299 Gaming 7 motherboard and an Intel i9-7900X CPU. Based on our testing most Intel i9-7900X’s can hit 4.6GHz when using adequate coolers.


Hardware used in this guide


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

If you have never been inside your BIOS before welcome! No need to worry, we will guide you step by step with screen shots.


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

Enter “Advanced Frequency Settings”

GIGABYTE X299 Skylake-X advanced frequency settings

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.

GIGABYTE X299 Skylake-X xmp profile 1

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 memor 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 i9-7900X the CPU has a Base Clock of 100 and CPU Clock Ratio of 33 for a frequency of 100 * 33 = 3300MHz. Intel® turbo will boost to 4.5GHz but only on 1-2 cores at a time. In this guide we will be overclocking all cores to 4600MHz.

Set your CPU Clock Ratio to “46”.

GIGABYTE X299 Skylake-X cpu core ratio

Step 4: Adjust Turbo Settings

Enter “Advanced CPU Core Settings”

GIGABYTE X299 Skylake-X advanced cpu core settings

Set “Enhanced Multi-Core Performance” to Enabled

Set “Energy Effi­cient Turbo” to Disabled.

By default Turbo Mode boosts the 2 strongest cores to the highest multiplier while leaving the rest at a lower multiplier. Enhanced Multi-Core Performance boosts all cores to run at multiplier we set in step 3.

GIGABYTE X299 Skylake-X energy efficient turbo 

Step 5: Change CLR (MESH) Ratio Frequency

The formula for CLR (MESH) frequency is CPU Base Clock * CLR (MESH) Ratio = CLR (MESH).

CLR (MESH) is Intel’s new inner chip communication architecture. Its frequency correlates to the non-core parts of the CPU such as cache, memory controller, and communication between individual cores. To start set your CLR to 32 and continue on with the guide. After you have determined your CPU’s highest multiplier you can re-visit your CLR settings. Preference should be placed on obtaining the highest CPU clock. In general higher CLR values do not produce meaningful performance differences, but they may improve benchmark score.

Set CLR (MESH) Ratio to “32”.

GIGABYTE X299 Skylake-X mesh ratio

Step 6: Adjust Your Voltage Settings

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

GIGABYTE X299 Skylake-X advanced voltage settings


Select the “Advanced Power Settings” Option.

GIGABYTE X299 Skylake-X advanced power settings

AORUS X299 motherboards are already optimized to reduce voltage fl­uctuation which is bad news when you’re overclocking. 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”.

GIGABYTE X299 Skylake-X vcore loadline

Step 7: 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”

GIGABYTE X299 Skylake-X cpu core voltage control

GIGABYTE X299 Skylake-X cpu vrin


CPU VRIN External Override: This is the total voltage going into the CPU. Raising this to 1.9 will improve benchmark scores when overclocking.

GIGABYTE X299 Skylake-X internal cpu vcore


(Optional) Advanced Settings

The following are settings you might sometimes need to change when OCing 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 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 1.4v depending on your CPU cooling solution. Most CPU’s should be able to hit 4.6GHz at this voltage, however CPU’s are not all created equally. Some may need more voltage, some less.

Set Vcore to “1.25” to start. If you system is not stable raise the voltage in increments of .01 with a maximum recommended voltage of 1.3.


CPU VCCIO and CPU System Agent Voltage:

Both of these settings help when we overclock the DRAM frequency. In our testing we did not gain any performance above 1.25V, however values up to 1.4-1.45V are ok if you are using air cooling. Since we used X.M.P. profi­les for our memory these voltages will be automatically set.


VCCIN voltage:

VCCIN is the voltage going to the chip itself, not to be confused with VCORE which is the voltage going to each individual core. By default this should be set to 1.8. You can set it to 1.9 for increased stability when overclocking, but it may result in higher CPU temperatures.


AVX Offset:

AVX Offset ranges from 1 to 5. When you set an AVX offset it will reduce the multiplier by 1-5 (whatever you set it to) when running AVX instruction sets. AVX offset is found under M.I.T -> Advanced Frequency Settings -> Advanced CPU Core Settings.

GIGABYTE X299 Skylake-X avx offset

Step 8: 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”.

GIGABYTE X299 Skylake-X name profile

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

GIGABYTE X299 Skylake-X save 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 overly aggressive overclocks and you’ve lost all of your previous settings.

Step 9: 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.

GIGABYTE X299 Skylake-X save and exit


GIGABYTE X299 Skylake-X OC Stability Testing

Congratulations! You are now running at 4.6GHz, 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.


How to Stability Test

Step 1: Open up CPU-Z, CoreTemp, and Prime95. Make sure Prime95 is con­figured. Click Custom, change “Min FFT size (in K):” to 961344, and change “Max FFT size (in K):” to 961344, then check “Run FFTs in-place” and then press OK to start.

GIGABYTE X299 Skylake-X prime torture test
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.
GIGABYTE X299 Skylake-X Coretemp


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 1.4 volts if possible. After making adjustments 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 4.6GHz on Prime95 you can try setting AVX offset to 3. If using a newer version of Prime95 you can also set AVX 512 to 5. This will lower your CPU multiplier by 3x when running AVX and 5x when running AVX512 instruction sets. For instance if your CPU is set go 4.6GHz it will run at 4.4GHz when running AVX and 4.1GHz when running AVX512 programs.


Step 3D (If System Shuts Down): AVX workloads such as Prime95 v27.9+ are some of the most demanding workloads to put on a processor. As a failsafe your system will shutdown if the CPU is drawing too much power. You can override this in the BIOS under Advanced Power Settings by setting CPU Vcore Current Protection to Extreme. This setting should only be used during carefully monitored benchmarking sessions. It should not be needed for normal daily workloads or gaming.


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 4.7GHz non-delidded CPU on air:

GIGABYTE X299 Skylake-X Prime95

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 15-30C on 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 online through 3rd parties.

GIGABYTE X299 Skylake-X Delid Tool


GIGABYTE X299 Skylake-X Core i9 7900X OC Results

We’ve increased frequency from stock to 4.6GHz. The results of our overclocks can be seen using the Cinebench 15 benchmark below.

Stock 4.6GHz
GIGABYTE X299 Skylake-X Stock Cinebench GIGABYTE X299 Skylake-X OC Cinebench