How to overclock Intel i7-5820k

Last year we have upgraded our computers in our workstation offices in North London – Palmers Green.
We have gone for following components:

  • CPU: Intel Core i7-5820K, 3300 MHz (4700 MHz OC)
  • CPU Cooler: Kraken X61
  • Memory: G Skill F4-3000C15-4GRR 16GB
  • Motherboard: Asus X99-S  (1 PCI-E x4, 5 PCI-E x16, 8 DDR4 DIMM, 1 M.2, Gigabit LAN, Audio)
  • PSU: 850W EVGA SuperNOVA G2
  • Graphic Card: NVIDIA Ge Force GTX970
  • Sound Card: Creative Recon 3D
  • Primary HDD: SAMSUNG SM951 MZHPV256HDGL-00000  (256 GB, PCI-E 3.0 x4)
  • Secondary HDD: 3 x WD Green WD30EZRX  (3 TB, SATA-III)
  • Monitors: Dual HP Z30i IPS Display
  • PC Case: Define R5

Since we don’t play any games, we thought this setup should be sufficient for our daily tasks. We run Windows 10 PRO, dual boot with Hardened Gentoo x64 and few Virtual machines (all with Debian).

Ok, so you are now know our configuration, let’s get going with overclocking, we wanted to achieve at least 30% but end up with even more – 42%

Overclocking guide

Step 1:

Remove all Asus OC software as we are going to do manual overclock in BIOS. Please make sure you have the latest BIOS.

Also make sure your CPU cooler is sufficient enough to handle this beast.

Let’s enter the BIOS and go to:

Set OC Tuner to XMP and CPU Strap to 100MHz.

Set BCLK Frequency to 100 – increasing this will also increase memory frequency (Memory speed= BCLK * Memory multiplier). We have tried playing with this setup increasing BCLK, but we could not get stable overclock at 4500MHz+

Leave anything else in this section on Auto as Asus motherboard will take care of anything else.


Step 2:

Scroll down in this section and make sure all voltage below are set to AUTO, there is no need to adjust them as our motherboard will set them up automatically and won’t go over the limits.

Step 3:

One of the most important step in CPU overclocking, here we adjust CPU Multiplier (CPU Speed= BCLK * CPU Multiplier)

Select Sync all cores from CPU Core ratio option.

On Intel i7 5820k you can easily set this up at 40 at the beginning and start increasing it once you test stability of your OC.

Step 4:

Most important step, setting Core Voltage of our CPU.

Set CPU Core Voltage to Adaptive Mode

Offset Mode Sign to +

CPU Core Voltage Offset to Auto

Leave all other settings on AUTO as they will be set up automatically.

If you see CPU Input Voltage going above 1.950, then set it up manually at this value, or leave AUTO if it stays below.

Now under Additional Turbo Mode CPU Core Voltage set at 1.290 at the beginning. Keep this value under 1.300 for 24/7 OC profile.

Step 5:

Here we start to play and try to find the right balance between CPU multiplier, Vcore and CPU temps.

Install Intel Extreme Tuning Utility for a quick benchmark.

Set Vcore on value in step 4 and start increasing multiplier.

Set CPU multiplier to 41, boot to Windows, run stability test with Intell XTU. This software will usually detect invalid settings right away, resulting in BSOD or restart.

If you passed OC Test, boot back to BIOS, increase CPU multiplier and repeat the process.

When you get Blue Screen, decrease CPU multiplier to last good settings.

Once you found your “magic” CPU multiplier number, go back to Step 4 and start decreasing Additional Turbo Mode CPU Core Voltage by 0.005

Repeat the test with Intel XTU and keep decreasing Vcore until you find your “magic” value.

Step 6:

Once you find your “magic” numbers it’s time to do full stress test.

Run Intel XTU and setup stress test for at least 5 hours. Use RealTemp to monitor your Core temperature. Keep Core temperature under 85C.

Every chip is different, overclocking results may vary, but if your chip is capable of 4500MHz under 1.300v Vcore then you are lucky.

We have been extremely lucky with ours achieving 4700Mhz at v1.285 

Below are few screenshots from CPU-Z and RealTemp (idle and stress).


i7 5820k overclocked to 4700MHz with Vcore 1.285

i7 5820k 4700MHz CPU temperature idle

i7 5820k 4700MHz CPU temperature full load

Good luck with your overclocking, let us know your results in comments below.

PCMarc Team