Overclocking the Core i5-7640X (Kaby Lake-X) to 5.1GHz in 3 Simple Steps

In this article, we’ll show you how to overclock the Intel Core i5-7640X (Kaby Lake-X) from the default speed of 4.0GHz to a whopping 5.1GHz, by simply changing 3 BIOS options on the ASRock X299 Taichi motherboard. You can check out the review of the ASRock X299 Taichi motherboard here.



The Core i5-7640X (Kaby Lake-X) is the entry-level processor on the Intel’s Core-X series. But that doesn’t mean it’s bad, quite the contrary. It is in fact better at reaching higher overclock speeds because of the lower number of cores.


  • Supported Memory: DDR4-2666
  • Socket LGA 2066
  • 6MB L3 Cache
  • Compatible with Intel X299 Chipset Motherboards
  • Max Turbo Frequency 4.2 GHz
  • Unlocked Processor
  • Cooler / thermal paste not included



According to Intel’s specifications, the Core i5-7640X has a TDP of 112W, which means it runs pretty hot, hotter than your standard Kaby Lake (i5-7600K has a TDP of 91W). We highly recommend using a good all-in-one liquid cooler (AIO). See our test rig below. In this example, we used a Cooler Master MasterLiquid Pro 240 AIO.


Before we start, here’s a quick disclaimer:

Disclaimer: Overclocking is never guaranteed, so the results may vary depending on certain conditions and various hardware configurations. I am not recommending overclocking if you do not know what are you doing. High voltages may damage hardware and it will not be covered by warranty.



The BIOS settings

After some tweaking in the BIOS, I was able to overclock the Core i5-7640X from a default of 4.0GHz to a whopping 5.1Ghz. That’s an extra 1.1GHz overclock … not bad!

Here’s a screenshot of the BIOS settings to achieve my overclock in 3 simple steps.

  1. Set the CPU ration to ALL Core to 51
  2. Set the CPU cache ratio to 40


3. Increase CPU vcore to 1.35V

Everything else was left at default or Auto.  

Now that we’ve managed to overclock the Core i5-7640X to 5.1GHz, let’s check out the full load temperatures on our next page …


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About Winston 3632 Articles
Winston has over 20 years of experience in the I.T. Industry. He launched Funky Kit with the aim to capture a wider audience worldwide. His knowledge in PC hardware is very distinguished, not only publishing enjoyable reviews but also writing great articles.