3 Step Overclocking Guide – Sandy Bridge (Miahallen)

April 22, 2013 in CPU, Intel, Overclocking, PC


I am not responsible for any bad things that happen to you or your computer as a result of you following this guide, nor is tekinferno.com. My goal is for this guide to be a safe overclocking guideline, however the burden for damaged hardware always lies on the user performing the overclock! Overclocking can damage hardware and in most cases will void your warranties.


In the prior version of this guide, I requested that you have some basic knowledge of your motherboards BIOS. While I have not addressed every motherboard on the market, I have included details for the top enthusiast brands. But as before, please do not be afraid to get into your BIOS and have a look around, if you are ever concerned that you may have changed a setting erroneously, you can always load defaults, and start over. Most boards have a CMOS reset button on them now-a-days, if not check your user manual for the location of the CMOS reset jumper…please ensure you know the location before getting started.

This guide is independent of your cooling system. Whether you are using the stock Intel cooler or if you’re pushing to the extreme with phase change cooling, the basic steps remain the same. One thing that is far too common are mistakes mounting your cooling system, specifically the application of the thermal interface material (TIM). If you don’t have much experience mounting cooling apparatus, please refer to this excellent guide from Arctic Silver.


Determining methods for finding a stable overclock are highly controversial, everyone has their own definition of a stable system, but when I refer to “stable” in this guide, I am referring to the stability of your selected “stability test.” So for a power user or gamer who wants a reliable system that won’t ever crash due to an overclock pushed too far, you’d need to test with a program that will load all of the cores and threads applicable to your CPU, OCCT and IntelBurnTest are two popular choices. OCCT uses the same algorithm as Prime95 but has a friendlier interface. IntelBurnTest uses the Intel linpack binaries to stress the system and also has an easy to use interface. In this guide I may use testing that is insufficient in your opinion. It is only a guideline and if you feel more testing is necessary for your system, by all means feel free.

So with that in mind, we will attempt to isolate each portion of the system and overclock one step at a time. This may seem time consuming at first glance, but rest assured this will potentially save you hours of troubleshooting and frustration. So go slow, and follow each step very carefully.

BIOS familiarization

If you’ve found my guide online, my guess is you’re looking for more than a basic overclock. If you’re not, and all you’d like is something simple, please redirect your attention to your motherboard manufacturer’s website and download the latest overclocking utility. For basic 10-20% overclocking, they work pretty well. There is “Gigabyte EasyTune6“, “Asus TurboV EVO“, “MSI Control Center“, and “eVGA eleet“. This guide is written to take it to the next level, for THAT we need to do the overclocking from the BIOS.

Speaking of which, before we begin, please check your motherboard manufacturer’s website for the latest version of your BIOS. Usually enthusiast level boards will have BIOS engineers tweaking them for months or years to improve overclocking support. Unless you have a reason to stay with your current BIOS, I’d suggest updating to the newest version.

If you don’t know how to access the BIOS, please refer to your motherboard’s owner’s manual for instruction. While you’re there, find out how to “clear CMOS”. As I mentioned in the introduction to this guide, it’s important you know how to properly “clear CMOS” before we begin.

Secondly, the first thing to do after powering up the new system is to enter the BIOS and find the “hardware monitor” area and verify the CPU temperature is reasonable based on your cooling. If not, please power down the system and verify the mounting of your cooling apparatus (refer to the guide linked in the “prerequisites” section.


The variety of users reading this guide is vast, and each user’s goal will be unique and specific to his/her needs. It would be impossible for me to address every user’s specific needs. But I’ve attempted to be as broad, yet specific as possible. My goal is to assist the maximum number of users as possible, despite your specific needs.

Based on user feedback from the previous version of this guide, I decided to better address overclocking with power features enabled. The easy answer was to follow the old guide and then attempt to enable your power features afterward, but that rarely worked when approaching the limits of a given system.

Just as before, if you want to maximize your overclock, you should disable all the power saving features in the BIOS as detailed in step 1. However, if you’re after a more moderate overclock, and you’d like to save power (especially while your system sits idle) you can leave those setting enabled. Just follow the guide as written (I’ve added tips for you along the way) to find your best settings. While your potential overclock will be more limited, the benefit will likely be worth it to many of you.


I’d like to start off by writing briefly about the BIOS and more specifically, differences in terminology between the different manufacturers. Obviously there are too many motherboards on the market to show you every single one in this guide. But looking at boards from the four top manufactures, we should be able to better identify specific terminologies used by each.

Understanding “total system performance”

Before we go into how we overclock these CPU’s let us look at what determines how fast your whole system will run. CPU frequency is very important. However, there are many other factors that play into your total system performance. All of your primary BIOS overclocking revolves around the Base Clock or “bclock” and clock ratios. The base clock’s default speed for all H67/P67/Z68 based systems is 100MHz. overclocking methodology changes a lot with this new platform. We are no longer focused on bclock changes because Intel has buried the clock generator into the CPU itself, and has locked it down so only minor changes are possible.

Sandy Bridge die map

Sandy Bridge die map

CPU frequency = bclock x CPU clock ratio

This is a biggest change from the last generation (H55/H57/P55/X58) is that most overclocking will come from changes in the CPU multiplier, not the bclock. But the formula doesn’t change; the bclock multiplied by the CPU clock ratio will still determine your overall CPU frequency.

  • Core i3 & i5 2100 series = fully locked
    • These CPUs are “fully locked”, the multiplier cannot be increase beyond the factory setting.
  • Core i5 & i7 non-K series = partially unlocked
    • These CPUs are “partially unlocked”, the multiplier can be adjusted up to +4 the factory setting.
  • Core i5 2500K & i7 2600K = fully unlocked
    • These CPUs multipliers can be freely adjusted; in effect, they are “fully unlocked”.


H67/P67/Z68….what’s the difference?

There will be three “chipsets” supporting LGA1155 Sandy Bridge, from an overclockers perspective, here is the difference.

  • H67 will not allow CPU multiplier overclocking, only base clock, which as I’ve already mentioned is very limited. If you intend to overclock your CPU, please do not choose H67. Memory overclocking is still possible with, and the GPU integrated in Sandy Bridge is enabled with H67. Please don’t bother buying a “K” series CPU with H67, it will be a waste of your money unless you really need a stronger iGPU.
  • P67 will be the enthusiast choice for Sandy Bridge, it will allow CPU and memory multiplier adjustments for overclocking. P67 does not support the integrated GPU, if you plan to use the integrated GPU, please do not buy a P67 based motherboard.
  • Z68 Is now available and supports fully unlocked overclocking for the K series and is iGPU enabled. You will be able to adjust the CPU, memory, and GPU multipliers with Z68, a great choice if you plan to overclock and use the GPU. Also keep in mind, this would be a good choice for someone who’d like to run multiple monitors, but dedicate their discrete graphics card to the primary monitor.


Memory frequency = bclock x System Memory Multiplier (SPD)

Depending on the motherboard, memory overclocking is fairly straightforward with Sandy Bridge. Bclock multiplied by memory ratio will determine the memory frequency.

DDR – The other part that can be quite confusing for users who are not familiar with DDR technology is the difference between the memory clock speed and the memory’s DDR speed. For instance, DDR3-1600 actually runs at 800MHz, it’s just that DDR (or dual data rate) technology allows the memory to process twice per clock cycle. Back when we switched technologies from SDRAM to DDR for the first time, the manufacturers started saying DDR-400 when it ran at 200MHz because it was better marketing to sell their memory over the older SDRAM technology. This is why CPU-Z shows 800MHz for your DDR3-1600, or 1000MHz for your DDR3-2000.

Memory speed and bandwidth can have a huge effect in some applications, and negligible impact on others. But overall, top shelf memory is one of the worse items you can spend your money on from a value perspective. Faster CPUs and GPUs will give you much more performance for your hard earned cash.

Important Voltages when Overclocking

There a few important voltages which you will need to manipulate while overclocking; below are the primary ones. Not every motherboard BIOS is identical, but all enthusiast level motherboards should provide control of the voltages as shown below.

CPU Vcore – Directly related to the CPU frequency. As you increase the CPU frequency you would need incrementally increase the v-core as well. Sandy Bridge is very new, and a “safe” voltage range for long term reliability is not yet known. As we spend more time and learn more about this platform, I will update this guide with a more educated estimate. For now, I’d suggest staying below 1.45V or 80C load temperatures. I feel those are both fairly conservative settings. Another big change from previous architectures is that the L3 is now tied directly to the CPU for both power and clock speed. So, from an overclocking perspective, L3 is now part of the core, where it was previously part of the uncore.

For now, my recommendation is that while you are stress testing, monitor your CPU core temperatures with Real Temp and if the temperature is under 80C, you can increase the voltage up to 1.45V max. If you don’t mind the risk, feel free to push further and make sure to publish your results for the community to learn from, whether positive or negative.

Nothing I’ve ever used my computer for come close to generating heat like LinX. Because it generates so much heat, it has become my favorite stress testing application. As long as I can keep my CPU cores below 80C while running LinX, then for me that’s safe. If you are more conservative/cautious than me that’s perfectly OK.
*** NOTE *** Please ensure you’re running Windows 7 with SP1 for LinX testing, it enables AVX which increases temps a fair amount.

Load Line Calibration - This actually goes by a few different names, but they are all meant as a means to reduce or prevent v-droop. It does typically ease the overclocking process at the cost of violating Intel’s design specs. However, overclocking in its essence violates Intel’s design specs, so you’re not breaking any new ground with this feature. This feature was very useful for increasing the overclocking potential of the last few generations of Intel CPUs, and it’s already being effectively used with Sandy Bridge as well. For more insight on the theory of LLC, refer to this excellent explanation at anandtech.com. There was also some real world testing recently; feel free to check out Bobnova’s LLC investigation here.

VccSA – This is the voltage with controls the “System Agent” (new “uncore”). Since the L3 cache has been moved to the core, the only thing left on the System Agent that concerns us as overclockers is the integrated memory controller (IMC). It’s already been discovered that the IMC on Sandy Bridge is quite robust, and usually won’t need any additional voltage for speeds up to DDR3-2000 and possibly even higher. I found I needed about 1.15V for maximum potential when running very fast memory speeds. This may also be important with very high density DIMMs or when fully populating the DIMM slots on your motherboard. At this time, I would caution using any more than 1.2V on the VccSA.

VccIO – This is the voltage which controls the SA’s IO. Many users and manufacturers are taking issue with my claims of the SA voltage being most important for IMC overclocking. While I cannot explain my personal results, they definitely go against the majority. With that being said, the motherboard manufacturers and many uses will tell you to only adjust the VccIO, and leave the VccSA alone…I’m recommending you try both, and see which works better for your CPU. My testing was difinitively VccSA reliant. At this time, I would caution using any more than 1.2V on the VccIO.

DRAM voltage – This is directly related to your RAM modules and increases will allow increase in MEM speeds. There has been a lot of debate as to the limitation 1.65V limitation Intel has published. With the older platforms, the rules no longer apply. With a few months past now, it seems safe to say that this platform is robust enought to handle running memory at higher voltages, at least for the short term. Many overclockers still want to push the limits, but since all the current memory seems to scale less with voltage than older stuff, this is becoming a moot point. I’d still suggest staying at 1.65V or below for a regular daily system, but I’ve pushed up to 1.85V for short benching sessions without any adverse effects.


Sample overclocking goals to use as a reference

I decided not to use “sample systems” as in the last few guides. Because of the vastly different methodology used in this overclocking process, I don’t believe they’ll be helpful this time.

Next: 3 Step Overclocking Guide Continued…

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