Intel Ivy Bridge Socket 1155 OC Guide


Note: Overclocking might lead to a loss of warranty and damage components. However, if you follow the instructions of this guide, you should not experience any issues. If you want to know more about the risks of overclocking, simply check out this guide.


Ivy Bridge basic knowledge #1

Ivy Bridge CPUs are based on the previous generation Sandy Bridge. But the production process was reduced from 32 to 22 nm. In addition, Intel invented the Tri-Gate-Transistors with this generation. The result is a even easier overclocking process and better overclocking results on ambient temperatures. Compared to Sandy Bridge, Ivy Bridge also scales very well with lower temperatures. So you can improve the overclockability not only by adding more voltages, but also by using better cooling solutions like watercooling.


Ivy Bridge basic knowledge #2

The CPU core clock is a result of the Base-Clock (BCLK) and the multiplier of the CPU. Same goes to the memory clock which is also a result of BCLK and a multiplier.


101,47 BCLK x 44 Multi = 4464 MHz CPU Clock
101,47 BCLK x 24 Multi = 2435 MHz RAM Clock

Assuming you are using a CPU with “K” suffix, the overclocking will be very easy. It’s possible to just increase the CPU core clock by raising the multiplier in steps of 100 MHz. However, I recommend to adjust some more settings in order to achieve the best overclocking results.

If you have a CPU without “K” suffix, you have to increase the Base-Clock to overclock your system. Usually I don’t recommend this, because the BCLK is tied to the PCI-Express clock and DMI-Connections which can cause instabilities even though your CPU is still stable at the given core clock.

However, it can still be worth it to take a look into your BIOS. For example a i5-3450 CPU usually clocks at 3100 MHz (31 x 100 MHz), but you should be able to raise the multiplier up to 37 which results in 3700 MHz and an increase of about 17 percent.

Some Intel CPUs feature a so-called turbo clock. For example the i5-3330 has a stock clock of 3000 MHz on all cores with a turbo clock of 3200 MHz on a TDP of 77 W. This means if you run an application which is only single threaded, the CPU can clock up to 3200 MHz on one or two cores, because it doesn’t reach the full load of 77 W.

You can change this limit by raising the maximum TDP in the BIOS to e.g. 150 W and also manually raise the multilpier of all cores to 32, so you have a constant full clock of 3200 MHz on all cores.

Reminder: Always keep an eye on your temperatures. Ivy Bridge CPUs have a maximum temperature of 105 °C. But I recommend to stay below 90 °C to prevent long term damages.


Overclocking Step-by-Step

I’m using a GIGABYTE Z77X-UD3H in combination with a i7-3770K for this guide which is a mainstream Z77 mainboard. You can apply these settings for other mainboards as well. I’m currently also working on guides specified for other mainboards and will add them as soon as possible.

Step 1: Voltages

For moderate overclocking without any risks you simply have to fix the voltages at their stock values first. So go to the BIOS, read out the stock voltages and fix them. The voltages are related to CPU and mainboard and differ from setup to setup. These are the stock values of my setup:

DRAM Voltage: 1,350 Volt (depends on the memory kit you use!)
CPU VCORE: 1,130 Volt
CPU VTT: 1,050 Volt
CPU PLL: 1,800 Volt
IMC: 0,925 Volt



Usually the stock voltages are safe settings and you can already overclock your CPU without raising these values. This means you don’t risk high temperatures, but still gain free performance.


Step 2: BCLK and Multiplier

In addition to the voltages, I recommend to manually fix the BCLK and multiplier. Set the BCLK to 100 MHz in the BIOS and the multiplier to 43, so you will start with 4300 MHz. Most 3770K CPUs will be able to boot with this clock on stock voltage, but some might be already unstable at this core clock. Simply try to boot into windows and check with Prime 95 if your system is stable. (Here is a simple guide how to use Prime95)


If it doesn’t boot or crashes during Prime95, lower the multiplier to 42 and try again.


Step 3: TDP-limit and energy saving options

Some energy saving options will cause the CPU to clock down in idle. These features are called C-States. If you don’t want your CPU to lower the core clock, simply disable C1E and C3/C6. This might be needed if you push your CPU to really high clocks.

Depending on which motherboard you use, it might be necessary to adjust the TDP-limit of your CPU. If you can successfully set the multiplier to 43 in Step 2, you can skip this and continue with Step 4. Otherwise disable the Turbo option or adjust the Turbo power limit to about 150 W. If possible I always completely disable the Turbo, to have my CPU constantly at the same clocks on all cores.



Step 4: Adjust your RAM settings

A common mistake is to ignore the memory settings. If you buy e.g. a 2400 MHz memory kit and just mount it in your computer, it will not automatically run at these clocks, because they are not officially supported by all CPUs or motherboards. In order to get the RAM to run properly you have to adjust the settings manually or load the XMP (Xtreme Memory Profile) settings.

If the XMP does not work, you can set the clocks and timings manually like I did in the example below. I used a 2 x 4 GB memory specified at 1866 MHz 9-9-9-24 at 1.50 Volt.

Simply enter the main timings (CAS Latency, tRCD, tRP, tRAS) according to your memory and adjust the memory frequency. Also don’t forget to fix the memory voltage. Some kits are specified at 1,65 Volt. If you have such a kit, go the voltage settings and adjust DRAM voltage (Step 1).

Note: For 2200 MHz and above, it might be necessary to raise the VTT and IMC voltages. You can read more about this later in advanced overclocking.





Step 5: Test your settings with Prime 95

To test your settings I recommend to use Prime 95. Keep in mind to keep an eye on the temperature during the stability test. You should not exceed 90 °C.

Here is a simple guide how to use Prime 95

If your system is stable at the given clocks and voltages and stays below 90 °C, you can increase the clocks and see if it’s still stable. If the system crashes and you are still below 90 °C, simply increase the core voltage (CPU VCORE) in small steps e.g. from 1,130 Volt to 1,150 Volt and test again.


Advanced Overclocking

Once you found stable basic settings, you can move on with proper overclocking. It can be useful if you use software overclocking tools to find stable settings in windows. For GIGABYTE mainboards you can use EasyTune 6 which is the full tool including features such as hardware monitor or details about your graphics card.

EasyTune for Z77
42.59 MB | 6428 downloads

1 2 3

However, I recommend to use the GIGABYTE Tweak Launcher which is a lite version of the EasyTune 6 and works a lot better from my experience

Tweak Launcher (GTL) for Z77
5.69 MB | 1385 downloads

In addition to the normal voltages and multipliers, it also gives full access to the memory timings.



The following table shows all important voltages for Ivy Bridge, explanations and the recommended values for your usage.



Loadline Calibration

The Loadline Calibration might help you to reduce the voltage drop from idle to load and also to stabilize your clocks. But it will lead to a higher temperature on the VRMs of your mainboard. Since the Z77X-UD3H has quite efficient VRMs, it’s no problem to set the LLC to Turbo. These are the settings I used:



Memory Overclocking

Usually memory clocks up to 2133 MHz are absolutely no problem on Ivy Bridge CPUs. However, if you want to use high-end kits with 2400 MHz and above, you might be limited by the IMC (Integrated Memory Controller) of your CPU and/or the mainboard.

I used a 2400 MHz kit from Kingston for this test which is specified at 2400 MHz 11-13-11-31 at 1,65 Volt. By simply loading the XMP profile or entering the values manually, the setup will not boot. It will be either stuck at boot code 51 or 15 which is an indicator for faulty memory. By increasing the IMC and VTT voltages, I could solve this issue. I increased the IMC voltage by +25 mV (0,95 Volt) and the VTT voltage by +25 mV (1,075 Volt). Using these voltages, I could boot without any issues.

Questions or suggestions about this guide? Simply leave a comment and I will reply as soon as possible.

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  • Tijmen

    great basics, thanks!

    I must add that Load-line calibration doesn’t only increase VRM temps, but also the actually applied voltage to the CPU core. So the core voltage will be higher than you set-up in the BIOS. Which might lead to higher temperatures and more strain, and hitting the 90 degree roof a lot sooner. The highest LLC setting is not always the best. it’ll just add more voltage to the core to ensure headroom, but it can give too much headroom, so lower it down a bit if you are hitting the temperature roof.

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  • Joerg

    Do you know, which 1155 Mainboard don’t limit the CPU?

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