As with any advice given at THGF regarding overclocking, neither I 4ryan6, Toms Hardware Guide, or the owners Best of Media are taking any responsibility for your overclocking your own hardware, you take sole responsibility for your own actions!
This guide is written assuming you are familiar with your BIOS and how to maneuver in it, change settings, and Clear CMOS and start over from scratch when needed, and also that you will be able to understand that unfortunately each different brand motherboards uses different BIOS terminology. (It would be a great day for overclockers if all motherboard vendors adopted a common BIOS terminology, but until then Google!)
Danger: Going past 1.500v is not recommended unless you have an extremely good cooling solution, meaning high end water cooling, air cooling is not a sufficient cooling solution for the heat this overclock generates, or you will be thermal throttling and not realize it. If you choose to disable thermal throttling you could very well loose your CPU from the voltage/heat required to reach the higher multipliers, remember 1.520v is Intel's tested maximum limit at the time this was written! See: Page 75 Table 7:1
The method I'm going to share here disables all Intels energy saving features, it also disables Turbo Boost, so if you want to run those features, stop reading right now, this is not the guide you need.
This guide will allow you to overclock all 4 cores, with no voltage or multiplier throttling, once again, make sure you have more than just adequate cooling, when overclocking all the cores.
Memory Note: The Sandy Bridge CPU memory controller is designed to run at either 1066mhz or 1333mhz any memory speed past 1333mhz is overclocking the CPU memory controller so you don’t want to overclock the memory from the beginning you need a solid memory foundation to overclock from, or you may be starting out already unstable and never be able to resolve it, no matter what CPU voltage you use.
It is important to manually BIOS set your Memory Timings and Memory Voltage requirements to 1333mhz (Very Important) This will be your best initial route to take, you want your memory literally bulletproof and stable when raising the CPU multipliers to higher levels.
Forget XMP preset profile at this point and research your memory at the website to discover what timings and voltage your memory can run at 1333mhz speed and manually set those timings and voltage!
AFTER! You arrive at a rock solid increased multiplier overclock, you can experiment increasing your memory speed to a higher setting, then if it won’t stabilize you can always drop back to your rock solid stable memory foundation speed.
Memory Note: 1T and 2T settings need to be tested for stability, I recommend you start with the 2T setting and when you reach your highest stable overclock, then see if it will remain stable if you use the 1T setting.
Every motherboard BIOS is different as to labeling each feature so it's your responsibility to discover your motherboards relation to these named settings, an ASRock P67 Extreme 4 is the motherboard BIOS these setting were taken from, I'm not making this long and drawn out so lets get down to business guys!
Disable these Intel CPU features, Enhanced Halt State (C1E), CPU C3 State Support, Package C State Support, C6 State usually on a Z68 M/B, Hardware Prefetcher, Adjacent Cache Line Prefetch, No-Execute Memory Protection, Spread Spectrum, Intel Virtualization (Unless you're running WinXP virtual within Win7, in that case leave it enabled)
Intel Speed Step Special Instructions:
Before you disable Speed Step, which disables Turbo Boost, set Turbo Boost Power Limit to [Manual]
Set Short Duration Power Limit to 140
Set Long Duration Power Limit to 180
Set Long Duration Maintain to the max allowed sec. (Mine is 56)
Additional Turbo Voltage (Mine is set to +0.527 and is working fine, Too little is not good and too much is not good, you'll have to figure this one out for yourself, if the voltage I'm using will not work for you)
BIOS save these special instructions exit and re-enter the BIOS and then disable Intel Speed Step
Some motherboards may allow the BIOS saving of the Intel Speed Step special instructions all in one step, my ASRock P67 Extreme 4 motherboard would not.
Leave CPU Thermal Throttling and Internal PLL over voltage, [Enabled]
Active Processor Cores = All
Core Current Limit = 200 (This is a wattage setting.)
CPU Ratio = Manual (This is the control to manually set your multiplier)
Host Clock Overide or Base Clock = 100mhz ( Do not increase this BCLK, you will be increasing the multiplier, not the base clock)
Power Saving Mode = Disabled
CPU Core Voltage = Fixed or Manual (However your M/B lists this setting to give you manual control over it)
Fixed voltage = ?.??? ( Whatever solid voltage it takes to run a certain multiplier, do not use Offset Voltage)
CPU Load Line Calibration = Level 1 (For an ASRock M/B is 1 to 1, you want as close to straight across voltage from BIOS to OP/SYS, since you will not be speed throttling down with these settings)
DRAM voltage = (You've already manually set that)
Leave all the rest of the voltage setting on AUTO, PLL, VTT, etc.
Now you're to a point where you simply trial and error boot to discover what manually set CPU voltage will stably run the multiplier you choose.
Baby steps is increasing one multiplier at a time until your auto voltage no longer supports the multiplier, it helps if you keep track of what auto voltage your motherboard is using for the multiplier it can support, as that sometimes gives you a starting place for manual CPU voltage setting.
However some motherboards use way too much voltage on auto so for a quick help regarding CPU manual voltage.
Most 2500Ks could run 45X or 4.5ghz somewhere between 1.300v ~ 1.335v depending on the quality of the CPU, trial and error booting will narrow down the voltage you'll actually need.
Most 2600Ks and 2700Ks took less voltage somewhere in the 1.270v ~ 1.300v for a 45x multiplier.
Note: All CPUs are different the voltages suggested could be either lower or higher, that's up to you to discover for yourself.
Testing to Stability:
When getting in the stability ballpark Intel Burn Test saves a remarkable amount of time vs hours of Prime95, use stress testing of your choice to arrive at the first step of stability!
Stress testing programs only test CPU and System Memory, they are not the total stability final say so, as some believe as they do not test Graphics, Sound, or Application or Operating System load, you need to continue testing for stability, to discover if you are using enough CPU voltage to support the multiplier you’ve increased to.
Continuing testing for stability, I suggest using a combination of benchmark programs such as Futuremark’s, 3DM06, 3DMVantage, or 3DM11, or 3Dmark, if you have the advanced versions of any of them you can max the testing settings, (Increase screen resolution, and add all the eye candy testing features, like Anti Aliasing, Antistrophic Filtering, etc. Max all you can) and run 2 or 3 loops.
If you encounter crashes increase your Vcore another notch and continue testing until you can run multiple loops without crashing, and you are pretty much there as far as stability is concerned, but continue and add some gaming with high graphic and sound, and if you have no crashes at all when sound is brought into the picture you’re good to go, if you do experience an in game crash bump up your Vcore another notch.
Always keep in mind, it’s desirable to run as low a Vcore voltage as you can, however it will take a certain voltage level to be 100% stable at the increased multiplier levels and there’s really no getting around that.
Additionally SLI or Crossfire setups usually require additional Vcore increase from the stability level of testing out a single GPU to stability.
It is just not necessary to run 24 hours of Prime95 as some suggest, you can do that and still crash a few minutes into a game, you’re only increasing the multiplier and Vcore voltage, all your other setting are default, so weeding out FSB instability is not necessary with this type of overclock.
Anyone reading this should know how important your cooling is, a good aftermarket cooling solution is an absolute must for reaching the higher multipliers stably, and you should monitor your temps with a program like Real Temp vs 3.70.
Good Overclocking to you and have fun! Ryan
More about :sandy bridge series multiplier overclocking
This Sandy Bridge guide has to a certain extent been rewritten and reposted as some new to overclocking seem to still need it.
Different motherboards have varying BIOS terminology and some of the above is specific to ASRock, if you cannot make the comparative BIOS settings to your motherboards BIOS settings, try Googling first, if that is no joy post a question here, but please at least try to help yourself first, that's why this guide was originally written in 2011, so you could solve your own overclocking desires!
As long as you can read, and comprehend what you read, all you need to know is right here, the information has been tested over and over with no CPU or hardware loss, so good hardware overclocking luck, as all hardware overclocks differently, what works for Joe may not work for Bill, so be patient and you'll reach your overclocking goal, whatever it may be.