# Core i7 Overclocking Basics



## zAAm (Jul 30, 2009)

*zAAm's Core i7 Overclocking Basics Tutorial*​
I've been looking at i7 overclocking for a while now and have yet to see a proper, well thought out thread explaining everything there is to know about the subject. Although I don't presume this thread will fill that gap, I'll try my best to help out new users to get the most (or at least a reasonable amount ) out of their i7's with this basic instruction manual. I presume you already have a basic knowledge of overclocking. If not, please read this first. Right, let's get started!

*Ok, so I've got the chip, what's next?*

First things first, check that you have the *right hardware*! The right motherboard and memory will make a difference in your overclocking efforts. Choosing a* decent brand* motherboard (I would recommend an Asus or Gigabyte, but there are equally good ones out there and I don't believe I'm *entirely* impartial) will ensure that you can raise the base frequency more and with greater stability.

Regarding memory, try to get a *higher rated* speed so you have some overclocking headroom. I would recommend at least DDR3-1333 modules although DDR3-1600 would probably be best (I'll explain why a bit later). The use of higher rated memory modules is to give you more room to move between multipliers without overclocking the memory in the process and thus will give you a more flexible overclocking system. In the same breath though, since i7's have triple channel memory controllers, the use of anything higher than DDR3-1600 will likely result in only tiny performance increases. Timings aren't that important for our overclocking purposes so I'm not going to go too much into this subject, but tighter timings will definitely give better performance overall as lower latencies speed up the whole memory subsystem. Again, choosing a decent brand like Corsair, OCZ, G-Skill, Crucial or similar will give you more peace of mind and likely better stability overall, although as with most things, with higher priced RAM you get diminishing returns.

*Staying cool*

An important aspect of overclocking (if not THE most important) is *cooling*. You're stressing your components beyond their certified limits so they are bound to generate more heat than normal. Unfortunately, the i7 is no exception. Not by a long shot! Actually, it's one of the hottest chips out there, easily reaching 80 degrees celcius at stock frequencies when stress testing. 

*Measuring Temperatures*

Now, before I move on the actual cooling bit, let's just talk about *measuring the temperatures*. The best way would be some sort of calibrated external temperature measurement device but since most of us don't live in an electronic shop, the internal temperature diodes on the i7 will do fine. If you've ever tried to read the i7's temperature with different programs, you'll have noticed that most of them give entirely different readings. This is because Intel decided that the i7 should report its temperature as the *distance from the core's maximum temperature* (Tjmax in this case, which means the maximum junction temperature). Uhm, now how does this work in practice? If it reports a temperature of 30 degrees, it still has a 30 degree buffer that it can heat up before reaching its maximum temperature. This unfortunately gives false readings to older monitoring programs that don't specifically support the i7. I've been experimenting with a few programs and I've found two of them that give accurate readings:

_RealTemp 3.0 (TPU's own temperature monitor) 
HWMonitor 1.14 (CPUID)._

*Choosing a cooler*

First you'll notice I'm not going straight to overclocking since I* DO NOT recommend overclocking an i7 with its stock cooler!* I suggest you read that again to make sure you remember it. If you choose to use the stock cooler when overclocking, you have to be either *crazy* or *stupid*, since the temperatures can soar into the 90's or even 100's on load...

Again, I'll not go too much into this subject, as you'll find plenty of cooling threads on this forum, be it water or air cooling. I would recommend installing your cooling system and ensuring your load temperatures are* below 60 degrees* at least before attempting to overclock.

*Diving straight into the BIOS*

This is the place where the magic will happen. As you will find out, overclocking the i7 is a bit different than most CPU's, but once you get to know the settings it isn't difficult to understand all the underlying principles and how they influence your overclock. Although BIOS options differs between manufacturers (and even models), there should be options to set the following:

BClk/Base Clock/Base frequency
CPU Multiplier
Uncore Multiplier
Memory multiplier
Intel Turbo Boost
HT/Hyper Threading
Intel SpeedStep/Power management
CPU Voltage
QPI/Vtt Voltage
IOH/NB Voltage
Memory Voltage
Find these options in your BIOS and make sure you know how they can be changed and so on.

*Setting the frequency*

The first step to overclocking your i7 is setting the base frequency or base clock. On the i7 this will be 133MHz default. Ultimately, you'll be aiming for around 200MHz on this setting, but for now, just *set it at a more reasonable 150MHz*. I prefer doing my overclocking in smaller steps because it's easier to identify the components that are holding back the overclock. If you immediately set the base frequency to 200MHz and your system won't POST, there's a whole list of components that might be the culprit.  But don't worry, we'll get there eventually 

*Setting the multipliers*

Next, we are going to adjust the CPU, Uncore and Memory multipliers. 

The CPU Multiplier is just what it says, it determines the CPU core frequency as 'n multiple of the base frequency. For the i7 920 for example, the default CPU multiplier is 20x, which gives 133MHz x 20 = 2660MHz, the stock 920 frequency. We want to *keep this at the default setting of 20* (for the 920).

The Memory multiplier sets the speed at which the RAM operates. You'll need to make sure your memory can operate at the speed set by this multiplier. For now, *set this at 6x* (which equals a memory speed of 6 x 150MHz = 900MHz or DDR3-900) to make sure memory isn't holding you back from getting the maximum CPU overclock. If for some reason your memory modules won't boot at such a low frequency, try setting this at 8x until you've reached a high enough BClk frequency that the modules will boot.

The Uncore multiplier governs the speed at which all the components in the CPU other than the cores operate. Always ensure this multiplier is at least twice that of the memory multiplier. There are accounts that some motherboards won't boot when this multiplier is exactly twice that of the memory multiplier, so I recommend setting this at* 2x+1 *that of the memory multiplier. If you've set your *memory multiplier at 6x, this should be set at 13* (2x6=12+1=13).

*Disabling certain features*

Since we want to focus on getting the correct CPU frequency, I suggest you disable features in the BIOS such as SpeedStep and Turbo Boost as well as any other power management features that will cause the BIOS to alter the CPU frequency or voltage.

*Setting voltages*

Now, here comes the scary part . Your BIOS probably has a number of voltages you can set, but we will focus on setting the CPU and QPI Voltages at the moment. Since our memory is running lower than rated, we know they are getting enough voltage at this point.

Adjusting the CPU Voltage can be a tricky business and no two CPU's are alike. I would recommend setting the CPU Voltage from 1.25V (default) *to around 1.35V for a C0 stepping or 1.30V for a D0 stepping*. This will ensure the CPU has enough juice to stay stable at relatively high frequencies. This will differ greatly as you move between different Bclk frequencies and I would recommend you *don't exceed 1.4V* as most CPU's will not benefit from the added voltage and will produce significantly more heat. Notice that the voltage setting in the BIOS will be slightly higher than that actually recorded due to voltage droop (may be as much as 300mV!).

Next we will look at the QPI Voltage. This is another setting you will have to experiment with, but I recommend *setting it at around 1.30V to start* (just below the core voltage). You can always drop this voltage when conducting the stability tests later on.

The IOH voltage can be *left at default* for now (probably at around 1.1V). This setting might not need changing at all unless you increase bclk significantly and want to improve stability. Even then it probably won't have to be increased to anything above 1.25V.

*A note on HyperThreading*

It is largely accepted that turning HT off in the BIOS will allow for higher overclocks as the CPU will run slightly cooler. I for one prefer to leave HT on since I would need the additional threads more than faster individual threads because I am a huge multitasker. Again, this depends on what you use your computer for and it might be best for you to experiment with this setting on and off to see which delivers better results in your environment.

*Rebooting....*

Now the time has come to, you guessed it, *reboot* (I might suggest praying at this point  ). If your computer POSTS correctly with no errors, check in the BIOS if the temperature is still low enough and then boot into Windows (Or possibly Linux if you prefer). I would suggest you then check the temperatures again with one of the above mentioned programs to determine the approximate idle temperature. If your PC does NOT POST correctly, you'll need to double check that all the settings are correctly set and that your CPU voltage is high enough. I haven't heard of a single i7 user who couldn't POST with a Bclk of 150MHz so I believe you'll be safe here. However, if this should happen, you could try increasing the CPU voltage.

Now, if this temperature is decent (around 40 degrees celcius or lower), run a stress testing program (preferably OCCT or Prime95 or something that stresses ALL 8 threads! Or 4 if HT is turned off) while checking the temperatures for around 15min. If the *temperature peaks at around 70 degrees you're still okay*.

If the test succeeds, I suggest you repeat the whole process, increasing the Bclk by 10-20MHz each time, while ensuring the memory and uncore multipliers are set accordingly, until you find that you've reached your target frequency.

If the test fails, try increasing the CPU voltage a step to add some stability.

*Stability*

When you've reached your target (possibly 200MHz Bclk, 4GHz CPU), I would highly recommend running the stress testing programs again but for a much longer period this time to ensure your CPU will be stable at this frequency. I'd recommend running OCCT or Prime95 for *at least an hour*. If the test passes without errors and the temperatures are within limits, you have yourself a certified, overclocked, beast of a CPU! 

*Final Thoughts*

If there is anything you wish to add to this guide or if you wish to point out an error, please feel free to notify me 

Happy Overclocking!


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## n-ster (Jul 30, 2009)

1st of all, good effort on this... Though I do not agree with everything, overall it isn't bad!





zAAm said:


> Regarding memory, try to get a *higher rated* speed so you have some overclocking headroom. I would recommend at least DDR3-1333 modules although DDR3-1600 would probably be best (I'll explain why a bit later). Timings aren't that important for overclocking purposes so I'm not going to go too much into this subject, but tighter timings will give better performance overall. Again, choosing a decent brand like Corsair, OCZ, G-Skill or similar will give you more peace of mind and likely better stability overall.



I disagree with most of this statement... First of all very fast RAM won't help much for performance at a certain point. If I would buy memory, it would probably be Crucial ddr3 1066 cas 7 (or 1333 cas 9 same RAM)... Timings DO make a difference. A DDR3 1066 cas 3 (doesn't exist) would beat a ddr3 2333 cas 12 anyday. Now the set of Crucials I was talking about (http://www.newegg.com/Product/Product.aspx?Item=N82E16820148246) are better than most memory performance wise and they are cheaper than most too. I suggest getting these sticks because wasting money on memory is not very smart. Just as an example, most people have brought these sticks to 2 ghz! I suggest that for any memory, to not go over ddr3 1600 and then just lower cas, since speed increases after 1600 are BARELY noticeable.

If I have time I may comment on the rest but until then, I want to know you still did a good job


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## DarkEgo (Jul 30, 2009)

Not bad, there could be more but still a very good guide. Good job!


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## n-ster (Jul 30, 2009)

Perhaps we should also suggest good hardware for i7's? example the RAM I talked about earlier and say for the mobo the UD3R.... Talk about hoew buying high end for i7 isn't much better than low-end?


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## zAAm (Jul 30, 2009)

n-ster said:


> I disagree with most of this statement... First of all very fast RAM won't help much for performance at a certain point. If I would buy memory, it would probably be Crucial ddr3 1066 cas 7 (or 1333 cas 9 same RAM)... Timings DO make a difference. A DDR3 1066 cas 3 (doesn't exist) would beat a ddr3 2333 cas 12 anyday. Now the set of Crucials I was talking about (http://www.newegg.com/Product/Product.aspx?Item=N82E16820148246) are better than most memory performance wise and they are cheaper than most too. I suggest getting these sticks because wasting money on memory is not very smart. Just as an example, most people have brought these sticks to 2 ghz! I suggest that for any memory, to not go over ddr3 1600 and then just lower cas, since speed increases after 1600 are BARELY noticeable.
> 
> If I have time I may comment on the rest but until then, I want to know you still did a good job



Thanks, and I agree with you n-ster, timings certainly make a difference. I'm not saying they don't, but I think when overclocking to 4GHz, it will be easier if you have a bit of headroom in your RAM specifically so you have a bit more room to move with the multipliers. I have 1333 RAM and I'm running them at 1200 at the moment because the next memory multiplier will push them to 1600, a bit too high for these sticks. I also agree that since these are running in Triple-channel, the bandwidth is more than enough and speeds higher than 1600 won't make a big difference in real world applications. The latency on the other hand would speed up the whole memory subsystem. Again, as you go to higher speed modules, the SPD's usually allow running at lower CAS latencies at lower frequencies, so you'll have that option as well. 



DarkEgo said:


> Not bad, there could be more but still a very good guide. Good job!



Thanks DarkEgo. I might add more a bit later, but I was thinking of making an easy to use, quick reading guide for people who aren't entirely new to overclocking but new to the i7 way. I referred in the first paragraph to the thread by xxxx which contains pretty much everything you need to know about overclocking, but nothing on the i7. If you have suggestions though, I would love to hear them


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## n-ster (Jul 30, 2009)

zAAm said:


> Thanks, and I agree with you n-ster, timings certainly make a difference. I'm not saying they don't, but I think when overclocking to 4GHz, it will be easier if you have a bit of headroom in your RAM specifically so you have a bit more room to move with the multipliers. I have 1333 RAM and I'm running them at 1200 at the moment because the next memory multiplier will push them to 1600, a bit too high for these sticks. I also agree that since these are running in Triple-channel, the bandwidth is more than enough and speeds higher than 1600 won't make a big difference in real world applications. The latency on the other hand would speed up the whole memory subsystem. Again, as you go to higher speed modules, the SPD's usually allow running at lower CAS latencies at lower frequencies, so you'll have that option as well.



Perhaps you would like to specify what I and you said better then  another thing that would be good to say it is REALLY not useful to buy expensive RAM... highest you should bguy 6gb is 100$, but the best would be something like 80-85$, hence why the crucials are good. Not only are they cheap, but those crucials OC ALOT.


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## DarkEgo (Jul 30, 2009)

n-ster said:


> Perhaps you would like to specify what I and you said better then  another thing that would be good to say it is REALLY not useful to buy expensive RAM... highest you should bguy 6gb is 100$, but the best would be something like 80-85$, hence why the crucials are good. Not only are they cheap, but those crucials OC ALOT.


QFT, mine run 1600 MHZ 6-6-6-18 1.5v. I LOVE them!


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## Mariusz803 (Jul 30, 2009)

Hey everyone,

I'd like to thank you zAAm for this post. Indeed for people such as myself who are just new to overclocking - this is a very helpful start.

I will be ready to overclock my i7 within a few weeks once i get proper cooling on the cpu. All other components are purchased and ready (will update system spec in my profile this week). My only request would be to include in this post what necessary steps to take if after you have overclocked, rebooted but cannot POST. I did read information on this somewhere but again i have to dig for it.

Thanks guys.


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## zAAm (Jul 30, 2009)

Mariusz803 said:


> Hey everyone,
> 
> I'd like to thank you zAAm for this post. Indeed for people such as myself who are just new to overclocking - this is a very helpful start.
> 
> ...



Your welcome! I've also added the information requested. I wasn't very clear on that. :shadedshu


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## n-ster (Jul 30, 2009)

But as he said, this is for people who are usually familiar with OCing, hence why he might have not made it very clear beforehand


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## Mariusz803 (Jul 30, 2009)

Thanks zAAm.

From the "Overclocking is Easy! Get Results!" it is mentioned to manually adjust all voltage in the system - no 'auto' enabled by bios. 
How critical is this for a beginner? is it necessary?


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## zAAm (Jul 30, 2009)

Mariusz803 said:


> Thanks zAAm.
> 
> From the "Overclocking is Easy! Get Results!" it is mentioned to manually adjust all voltage in the system - no 'auto' enabled by bios.
> How critical is this for a beginner? is it necessary?



As far as I know it's not necessary to specify ALL the voltages. You can leave things like pci-express and IOH and PLL voltages on default if you want. Technically you can leave vcore on auto, you just won't get anywhere with your overclock


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## grunt_408 (Aug 2, 2009)

zAAm said:


> As far as I know it's not necessary to specify ALL the voltages. You can leave things like pci-express and IOH and PLL voltages on default if you want. Technically you can leave vcore on auto, you just won't get anywhere with your overclock



Would it be better to at least manualy set all of the Voltages for everything to the default at least then you know things will be safe rather than leaving them on the "auto" setting?


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## zAAm (Aug 2, 2009)

Craigleberry said:


> Would it be better to at least manualy set all of the Voltages for everything to the default at least then you know things will be safe rather than leaving them on the "auto" setting?



I guess if you're really worried that the BIOS will auto overvolt your components then go ahead and do that


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## grunt_408 (Aug 2, 2009)

zAAm said:


> I guess if you're really worried that the BIOS will auto overvolt your components then go ahead and do that



What you said hehe. I already do that just as a rule that I learned on the Overclocking is easy guide. I cannot seem to get my i7 to 4GHz into windows dosnt matter I have been playing for a couple of days can most I can get is a 185 BCLK dosnt matter I think I will just try and tighten up memory for now and keep it this way untill I get IFX-14 backplate.


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## zAAm (Aug 2, 2009)

Craigleberry said:


> What you said hehe. I already do that just as a rule that I learned on the Overclocking is easy guide. I cannot seem to get my i7 to 4GHz into windows dosnt matter I have been playing for a couple of days can most I can get is a 185 BCLK dosnt matter I think I will just try and tighten up memory for now and keep it this way untill I get IFX-14 backplate.



Check in my sig for the i7 Overclockers Club. I'm sure you'll be able to get some help there


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## paulysvision (Nov 28, 2009)

if you buy 1600mhz ddr3 @ cas7 you will find that even with xmp you will only get 1333mhz at cas7 these figures are there maximums and no they dont hit both maximums  at default no ram that i have looked at(ALOT) has been able to hit there marketing specs by default i tested 1066mhz ddr2 c8 the other day can only hit c8 if frequency is lower than 700mhz so voltage increse would be needed and then your pretty much at full tilt with these sticks so dont look at there specs listen to these guys and other experienced people  talking about what they have done       its your best bet


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## Binge (Nov 28, 2009)

I'm not trying to crap your thread, but you should take a look at this.

x58 Overclocking, a Practical Guide

Any sections you would like to contribute to this stickied thread would be sited as your contribution.


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