Intel i7 4790K Devil’s Canyon Overclocking Guide

Well Folks, its time to dive into the world of overcloking the Intel Haswell CPU’s. Before we get ahead of ourselves, lets look at a few basic principles worth keeping in mind when overclocking a Haswell 4790k CPU.

Follow this guide at your own risk, some of these suggestions may or may not void your warranty, and/or damage your hardware. While it is unlikely that hardware damage will occur if proper precautions are taken, you have been warned.*
Overclocking in its most basic form is attempting to gain perfrmance by running some of the hardware in your PC at a higher operating frequency than was intended by the manufacturer.
To run things at higher frequencies, more voltage will be needed to support the components new higher operating speed.
With higher operating frequencies, and more voltage comes HEAT. When overclocking it is essential to monitor the tempratures of whatever hardware you are working with, in this guide it will be the CPU we will be focusing most on.
Overclocking is not suggested with the stock CPU cooler provided by Intel, it is highly recommended to upgrade to an after-market CPU cooler, that was designed with overclocking in mind.
With better cooling, you are able to run more voltage to support a higher operating frequency, without reaching the thermal limit of the chip. This will allow for better performance, while still maintaining safe operating temperatures. While these voltage limits are not exact for every situation, they are a good guideline.

• Stock Cooler – Voltage modification not recommended.
• High End Air Cooler – Do not exceed 1.175v
• Off the Shelf Water Cooler – Do not exceed 1.225v
• Budget Custom Water Cooling – Do not exceed 1.275v
• High-end Custom Water Cooling – Do not exceed 1.325

Temperatures should not be allowed to exceed 85 degrees Celsius for any extended period of time, to protect your CPU from potential damage. A good target temperature to keep in mind is around 77-80 degrees Celsius under load, however, this is a just a rough safe zone.Not all CPU’s of the same model (eg. 4790k) will be the same. The silicone in the dies are all slightly different, giving some better overclocking results. Some people may experience better results than others.

Now that we are through all of the guidelines, lets start with the overclocking! We will start off with getting familiar with some of the more basic BIOS functions and settings. (This guide was made using a R.O.G. Maximus Vii Forumla WC, some terms or settings may differ depending on specific hardware.)

The BIOS settings we will be working with in this guide will be:

• Ai Overclock Tuner – Allows you to select between Manual (full memory and BCLK adjustment) and XMP (memory and BCLK parameters automatically set)
• XMP – Allows you to enable differnet Extreme Memory Profiles with specific parameters predetermined for your memory (some smaller brands not included)
• CPU Strap – Used when modifying the BCLK frequency. (choose setting closest to BCLK frequency (will remain unchanged in most normal situations)
• BCLK Frequency – This is the base operating frequency of the CPU in simple terms. When multiplied with the “X”-core ratio, you get final the operating frequency.
• CPU Core Ratio – Allows you to choose weather the individual core ratios are controlled automatically, manually, or all cores synced to a manually set frequency.
• “X”-Core Ratio Limit – Allows you to change the multiplier of the specific core “X”, to change one or all of the cores operating frequencies
• Min. Cache Ratio – Sets the minimum operating frequency of the CPU cache
• Max. Cache Ratio – Sets the maximum operating frequency of the CPU cache. (commonly referred to as uncore)
• DRAM Frequency – Sets the operating frequency of your memory (this will be set automatically if XMP is enabled)
• CPU Core Voltage – Also commonly known as vcore, this is the voltage that is fed to the actual CPU cores
• CPU Cache Voltage – This is the voltage fed to the CPU cache
• CPU Input Voltage – This is the voltage fed into the CPU. (should typically be set to .4v-.5v over Vcore)
• DRAM Voltage – This is the voltage fed to your memory modules. To start, refer to your specific memory specs. (this will be set automatically if XMP is enabled)

Lets configure a basic overclock to get a starting point for your CPU. We are going to go for 4.4ghz at the lowest possible voltage. I typically use Cinebench as a quick test to see if the overclock is stable or not, however you can use whatever benchmark or stress test you prefer.

In your UEFI BIOS configure these settings, these are a great starting point

1. Set the Ai overclock tuner to XMP
2. Make sure the XMP profile the motherboard selects is the correct profile matching the specs on your memory
3. Leave the CPU strap on Auto (this only needs to be changed when modifying the BCLK for more extreme overclocking capabilities)
4. Make sure the BCLK is 100mhz (it should be by default)
5. Set the CPU core ratio to Sync All Cores
6. Set the core ratio limit of core 1 to 44. All of the other cores should change along with it. (Core ratio 44 x BCLK 100Mhz = 4400Mhz core frequency)
7. Leave the Cache ratios on auto for now.
8. Make sure the DRAM Frequency is set to its rated speed
9. Start with a CPU core voltage setting of 1.07
10. Make sure the DRAM voltage is set to your memory’s specific voltage (should be around 1.6v)

At this point navigate to the save and exit portion of your BIOS, and wait to see if your computer boots to the desktop. If it does, so far so good, its looking like you have a good chip. If not however, you arent out of luck, go back into your BIOS and change the CPU core ratio limit to 43 and try again. (43x100Mhz = 4300Mhz). If that does not work, continue to decrease the multiplier, one step at a time, until you make it to the desktop

Once you have gotten to the desktop, run Cinebench, or another stress test to see if the overclock is stable. If so, Great! If not, go back into your BIOS and raise Vcore by .025v and try again. Keep bumping it up by .025v until it is stable. Once this is done, you have your base stable overclock, which is a great starting point for future overclocking attempts. (it is highly recommended that you save your overclocking settings on a usb drive if your motherboard supports it, if not write down the settings you used for future reference.)

Now that you have found a stable baseline overclock, it becomes a process of tweaking individual settings until optimal performance is achieved. Lets continue to push the envelope a little bit further. How far you are able to go will depend on a variety of different factors, including but not limited to the quality of your specific CPU (typically thats luck of the draw), your cooling setup (more cooling will give better overclocking performance), and the other hardware you have chosen for your build.

Next you will need to raise the multiplier by one step, and try to boot, if it crashes, it isn’t a big deal, you will just need to add a little more voltage. Increase in .025v steps until you reach the desktop. (when increasing voltages remember to refer to the guide above to not exceed a safe CPU voltage for your cooling)

Once you have hit the desktop, the process is the same as before, run Cinebench or another stress test, and see if it passes. If it does, Awesome! If not, increase the voltage in .025v steps until it is stable.

Continue this process of stepping up the multiplier, and adjusting the voltage to achieve stability, until you reach your voltage or thermal limit, as stated above. Depending on your CPU and hardware, this could be anywhere from 4.4-5.0ghz. Don’t worry if it still isn’t where you would like it to be, this is just your maximum basic overclock, we are still only changing a few things to see if the chip is a good overclocker. The next step is where we will configure more a more aggressive, in depth overclock. (again, save this file one way or another).

So now you have your baseline overclock, and your maximum basic overclock (only changing a few settings, mostly multiplier and Vcore). Lets now push a little further to gain even more performance, while maintaining stability. We will continue to change the Multiplier and Vcore, but will also be changing settings regarding the CPU Cache, Memory, and also some more of the voltages. At this stage, monitoring your temperatures is essential.

Now we will set th CPU Cache frequencies, along with adding the voltage necessary to support it, along with the CPU input voltage to support the higher frequencies of both the cores and the cache. Here are some good CPU cache, cahce voltage, and input voltage starting points and things to keep in mind. We will be using the same benchmarks as before to test stability. When trying to stabilize an overclock, the time between hitting the desktop and getting it to pass benchmarks and stress tests, modifying all of these settings should help. Try to modify them one at a time, so you know what is helping and what is hurting. (specific values will vary CPU to CPU)

The Max Cache tends to be most stable around 300-600Mhz lower than the core operating frequency, with most. (Core 4700mhz – Cache between 4100mhz-4400Mhz)

1. Set min Cache ratio to 35-40
2. Set max Cache ratio to 40-47
3. Set Cache Voltage to 1.100v-1.200v (do not exceed 1.3v)

The CPU Input voltage needs to be raised, if it is no longer at least .4v more than Vcore. For example a Vcore of 1.325v would require a CPU input voltage of between 1.725v and 1.925v

Once you find a point where you have all of the new settings configured and stable (save it of course!) and continue to slowly step by step increase the core and cache frequencies, and their supporting voltages, until you find a point where you are happy with the performance, or are limited by either voltage or temperature.

Good luck in the search for those extra Mhz!