LGA 1156 Core i7 & i5 Overclocking Guide

andy5174

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This guide was written based on Core i5-750 CPU and Gigabyte GA-P55A-UD5 M/B!

This is for peoples who want to OC their PC but lazy to comprehend the basic knowledge of overclocking!
Thus, please don't criticize it for its unprofessional way of writing.

Warning: Overclocking DOES void the warranty. Neither TOM Hardware nor I will be responsible for any damage caused by overclocking!


0) HSF & Thermal grease

1) Decision making on the OC

2) How to start?

3) Voltages tweaking

4) Torture test


0) HSF & Thermal grease

- CoolerMaster Hyper 212 Plus has great performance for the cost.



- Prolimatech Megashadow is one of the top heatsinks which is paired with 2x 2000rpm 19dB CoolerMaster SickelFlow Fan here.




- Arctic Silver 5 is an excellent thermal grease with reasonable cost.



( Click here for the guide on thermal compound application! )


1) Decision making on the OC

What is the best OC?

Performance-efficiency wise

- The maximum OC that can be achieved near stock core voltage(1.20V shown on CPU-Z at 100% load).

- Power consumption increase is in LINEAR region! (The power increase in an exponential form after 3.6GHz -> Bad efficiency!)

For LGA1156 CPUs, 3.6GHz OC satisfies these two conditions.

Performance ONLY

The maximum frequency that can be achieved within the absolute maximum core voltage(1.55V for LGA1156 CPUs).

To be safe, you want to be within the maximum core voltage which is 1.40V for LGA1156 CPUs.

LGA1156 CPU Documentation from Intel!


2) How to start?

1. Enter the BIOS by pressing Delete key during POST(Power On Self Test)/Boot Screen.

2. Set BCLK, CPU multiplier/ratio, QPI Clock multiplier/ratio and Memory multiplier/ratio so that you can achieve the frequencies you want.

BCLK x CPU ratio = CPU frequency
BCLK x QPI ratio = QPI link speed -> set the ratio to the lowest possible value!
BCLK x Memory ratio = Memory frequency


My settings are:
CPU frequency: 180x20=3.6GHz
QPI link speed: 180x32=5.76GHz
Memory frequency:180x8=1440MHz
3. Manually set the memory timing according to the specification of your RAM, leaving everything unspecified as Auto.
(You have to set the DRAM Timing Selectable to Quick or Expert in order to do this in P55A-UD5!)

4. Disable the Turbo Boost Technology!

5. If it's impossible to get your system stable, disable C1E, C3/C6/C7 and EIST.

(C1E, C3/C6/C7 and EIST are power saving features and CPU will always run at highest clock when ALL of them are disabled.)

For i7-8xx CPUs, disable HT (Hyper Threading Technology) as well under this situation.


3) Voltages tweaking

Immensely useful information from Intel Datasheet! Give it a read before you move on, because it is going to help substantially in the following steps!


PCH: Intel P55 chipset voltage

- main I/O interface
- display connectivity
- audio feature
- power management
- manageability
- security
- Storage feature

It is pretty obvious that the higher the CPU frequency, the more frequent the I/O(input and output) and so the higher the power consumption of "main I/O interface". Hence, the PCH voltage needs to be increased based on the same current(P=VI). However, 1.10V should be sufficient for any OC achieved on air cooling.

PLL: Phase Locked Loop voltage

- Processor/IMC(Integrated Memory Controller)/other internal clocks
- Clock multiplying of processor is provided by an internal Phase Locked Loop

Generally, 1.8V(default value) and 1.9V for OC under 3.6GHz and 4.2GHz respectively.

Vtt

- L3 shared cache
- memory controller
- processor I/O power rail

Since memory controller frequency is dependent on BCLK, the higher the BCLK, the higher the Vtt required.
1. To achieve the absolute maximum OC, begin with applying the Maximum voltages(to be safe) or Absolute Maximum voltages(at your own risk) in BIOS.

(LGA1156 CPU Maximum/absolute Maximum voltage by Intel: Vcore= 1.40/[strike]1.55[/strike]1.40, Vtt= 1.155/[strike]1.21[/strike]1.40, Vram= 1.575/[strike]1.65[/strike]1.80, PLL= 1.89/1.98) with PCH=1.10

For i5-750 ONLY: The following settings are good points to start with!

In order to find out the minimum stable voltages, keep lowering the following voltages ONE at a time until your system becomes unstable.

(For example, varying ONLY the Vcore with all other voltages FIXED while trying to find out the minimum stable Vcore.)

The lower the voltages are, the cooler and healthier the CPU is!


3.6GHz:(24hrs Small FFTs test, 30hrs-2mins Large FFTs test and 14hrs-12mins Memtest86+ stable!)
Load-Line Calibration: Enabled (or Level2 for Gigabyte GA-P55A-UD5)
Vcore= 1.20V (CPU-Z idle)
QPI/Vtt/IMC= 1.14V
PCH= 1.10V
PLL= 1.80V
RAM= Specified voltage for your RAM

3.8GHz:
Load-Line Calibration: Disabled
Vcore= 1.264V (CPU-Z idle)
QPI/Vtt/IMC= 1.149V
PCH= 1.10V
PLL= 1.85V
RAM= Specified voltage for your RAM

4.0GHz:
Load-Line Calibration: Disabled
Vcore= 1.38V (CPU-Z idle)
QPI/Vtt/IMC= 1.25V <- Higher than absolute maximum Vtt
PCH= 1.10V
PLL= 1.88V
RAM= Specified voltage for your RAM

4.2GHz:
Load-Line Calibration: Disabled
Vcore= 1.43V (CPU-Z idle) <- Higher than maximum Vcore
QPI/Vtt/IMC= 1.30V <- Higher than absolute maximum Vtt
PCH= 1.10V
PLL= 1.90V
RAM= Specified voltage for your RAM
2. Set BCLK=210 with CPU Multiplier=20, (210,20), OR BCLK=200 with CPU Multiplier=21, (200,21), to make the CPU 4.2GHz which is the maximum on average chips.

3. Check for stability of your system:

- Stable: Jump to the next step, 4) Torture test, for thorough stability test. OR Set the BCLK and CPU Multiplier to (215,20 ) or (205,21) to get higher frequency.

- Unstable: Up the voltages at your own risk. OR Lower the BCLK and CPU Multiplier to (200,20) or (190,21) to be on the safe side. Keep repeating this until your PC is stable.


4) Torture test

1. Software required: CPU-Z, HWMonitor, Core Temp, Memtest86+ and Prime95

2. Run at least 12 hours Memtest86+ test and Large FFTs test of Prime95.

Monitor 100% load core temperatures

Make sure that your core temperatures are ALL within 72.7C which is the thermal specification from Intel!

p.s. Under 18C ambient temperature, my 100% load core temperatures are 48C-44C-44C-43C at 3.6GHz with the cooling solution specified earlier.
Prime95 Torture Test Options

- Small FFTs: CPU Stability test
- In-Place Large FFTs: Overall system(CPU/RAM Interface) stability test
- Blend: Memory stability test, NOT very useful! Use Memtest86+ instead

Click here for Prime95 instruction!
Go back to 3) Voltages tweaking and up the voltage a notch if it's not stable!

*Tip*: The best way to find out which voltage is causing the instability is setting the voltage that might be too low according to your 6th sense to its maximum value with ALL other voltages staying unchanged and see if the system is stable after this. If it is stable, then it's the voltage you need to tweak. If it is not, try tweaking another voltage in the same way.


For i5-750 ONLY: You might be extremely unlucky to have a chip that is much worse than the average with the stable voltages being much higher than those values given by me. What I would do under this situation is setting all the voltages to their maximum(NOT absolute maximum) values and lowering them ONE at a time until you get instability. However, try it again with C1E, C3/C6/C7 and EIST disabled before doing so.
(p.s. Maximum/absolute Maximum voltage by Intel: Vcore= 1.40/[strike]1.55[/strike]1.40, Vtt= 1.155/[strike]1.21[/strike]1.40, Vram= 1.575/[strike]1.65[/strike]1.80, PLL= 1.89/1.98)


N.B. Any OC below 3.8GHz should be very easy and don't go above that if either of your core temperatures or core voltage is already near its maximum specification at the point.


Good luck!

UPDATES:
28June10:
- Absolute Maximum Vcore, Vtt, and Vram change in latest Intel datasheet revision!
 

GBleezy

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Oh wow! This topic was sure a find for me! I was just looking for information on overclocking my Core i5-750 on an MSI P55-GD65 and stumbled upon this nice read!! Not to mention, i am just now looking in to this OC stuff because I just installed my brand new CoolerMaster Hyper 212 Plus w/Arctic Silver 5 and everything!! Thanks for the 72.7C temp limit! So is that a safe max load temp? Or is that like....you hit 72.9C automatic i5 paperweight? And all the other info on my CPU's voltages and the like! Bookmarked for reference :) :bounce:

Also I just OC'd my i5 750 to 21x181, which came out to 3.801GHz...I needed to boost voltages a few points to get it to boot properly and not bluscreen. Once it booted all stable I got and ran Prime95 through RealTemp 3.4...Anyways, at the peak of the heat-up portion of the test one core reached 74 and another 72, the rest under 65...But...I am wondering if that basically means end of the road for me? 3.801GHz as high as I'll be able to stabley compute? Feels like I could go 4.0Ghz easy if this thing cooled just a little better! I mean....I probably could go 4.0GHz+, but that don't interest me right now (maybe later)...I want to clock up to the fastest stable/usable speeds possible and be able to leave it there and use my computer without worry.

Also, does Prime95 pretty much get your CPU as hot as possible?? I mean sure it cooked my CPU up to 74C, but is there any applications that would get even cose to those temps under normal use? I mean, if I played Crysis right now in full detail at 1920x1200 my cpu wouldn't get close to those 74C temps would it?? Is it safe to say maybe that Prime95 Heatup Test will record a temperature at least 10C higher than any maxed out non-benchmarking application??
 

jsc

Champion
Moderator
Nice work. If I decide to go with an LGA1156 CPU, I'll start here. I won't need to reinvent the wheel. :)

And it doesn't hurt that Gigabyte is my motherboard of choice.
----------
Building computers since 1977.
Overclocking since 1978 - Z80 (TRS-80) from 1.77 MHz to 2.01 MHz
 

andy5174

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I used to be with ASUS all the time, but I am extremely happy with my current Gigabyte board.

It is cheaper and has more useful features than the ASUS equivalence.
 

srones

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Great writeup! I am getting my 750 in the mail tomorrow or the next day. I have a lot of work to do before I can worry about overclocking, but from all of my basic research, this will be my starting point. I have built a few computers, but this is the first one I have ever overclocked (plan to that is...). Thanks again for all of you work.
 

AMW1011

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I would like to say a few things.

First, the multiplier x21 is for Turbo and is not always usable for overclocking. Gigabyte says that it is impossible to overclock with the x21 multiplier, but some can. In my instance the Biostar T5XE can manage the x21 multiplier up to a base clock of 185, anything after will force the board to randomly lower the multiplier to x20 under load (this is a sign that the x21 multiplier is unstable).

Second I take serious issue with the notion to increase all the voltages to max spec level. I would only recommend increasing the PLL to 1.85v-1.9v and the VTT to 1.2v-1.25v. The CPU vcore should be left at stock and ONLY increased when unstable. I recommend increasing the base clock by 10 each time, then try to boot to windows and run 5 instances of Intel Burn Test at the maximum memory amount. If all is well, reboot and repeat. when you go over abase clock of 155-160 you may want to lower the base clock changes to 5. When you are over 180 you should definitely lower the increases to 5 clocks, if you haven't already.

One should never do something so rash with the voltage, if there is a problem it is best to notice it early on with the least voltage possible. From the forums that I used to be part of the posters would be appalled by such practices, but they seem to be accepted here and I am not sure why.

Thirdly, a lot of i5 750s, including mine, can hit those clocks at lower voltages, even though I admit those results are posted a lot in articles. For instance I am running my i5 750 @ 4.0 GHz with only 1.4v, still in spec. It is stable, I ran 20 passes of Intel Burn Test, 2 hours of Prime95 small FFTs, and 12 hours of Prime95 large FFTs.

Lastly DO NOT RUSH. It only took me a whole day to do it, but I did it 100% safely and I was more than willing to take more time if needed.
 

andy5174

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1. This is a guide for both LGA1156 i5 and i7. And the multiplier of i7 is? 21! In addition, you can use 21x on i5 as well as long as you are with the latest BIOS.

2. Read closely before you comment on something! I mentioned that the Max voltages were set ONLY when people are trying to achieve absolute max OC and asked people to keep lowering them to find the minimum stable voltage. You are definitely fine as long as you are within the max specification by Intel. In addition, exceeding the absolute max Vtt is REQUIRED for this kind of OC and I DID warn people by telling them do it "at your own risk".

3. The core voltage@4GHz mentioned is with LLC disabled and so it is much higher than yours. Again, read it closely before you comment on something.

4. I did 30 hours Large FFTs and 24 hours Small FFTs test which are much longer than your test. BTW, I had experience in failing torture tests after 20 hours SEVERAL times.

Why are there so many people like commenting something without first reading them closely these days? For example, this thread and the thread "CPU power saving features ON or OFF" started by me.
 

AMW1011

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Relax I was more commenting to add to your post, not contradict it. I knew what you posted, the voltage rant was more of a general thing, though I still disagree even if going for a max overclock. I was speaking from experience, and since I own an i5 750 I was speaking on the i5 750, sorry if that wasn't clear.

You need to relax, I wasn't calling you out just helping.
 

GBleezy

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Oh wow! This topic was sure a find for me! I was just looking for information on overclocking my Core i5-750 on an MSI P55-GD65 and stumbled upon this nice read!! Not to mention, i am just now looking in to this OC stuff because I just installed my brand new CoolerMaster Hyper 212 Plus w/Arctic Silver 5 and everything!! Thanks for the 72.7C temp limit! So is that a safe max load temp? Or is that like....you hit 72.9C automatic i5 paperweight? And all the other info on my CPU's voltages and the like! Bookmarked for reference :) :bounce:

Also I just OC'd my i5 750 to 21x181, which came out to 3.801GHz...I needed to boost voltages a few points to get it to boot properly and not bluscreen. Once it booted all stable I got and ran Prime95 through RealTemp 3.4...Anyways, at the peak of the heat-up portion of the test one core reached 74 and another 72, the rest under 65...But...I am wondering if that basically means end of the road for me? 3.801GHz as high as I'll be able to stabley compute? Feels like I could go 4.0Ghz easy if this thing cooled just a little better! I mean....I probably could go 4.0GHz+, but that don't interest me right now (maybe later)...I want to clock up to the fastest stable/usable speeds possible and be able to leave it there and use my computer without worry.

Also, does Prime95 pretty much get your CPU as hot as possible?? I mean sure it cooked my CPU up to 74C, but is there any applications that would get even cose to those temps under normal use? I mean, if I played Crysis right now in full detail at 1920x1200 my cpu wouldn't get close to those 74C temps would it?? Is it safe to say maybe that Prime95 Heatup Test will record a temperature at least 10C higher than any maxed out non-benchmarking application??
 

bob5568

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download a free utility called coretemp. It will show you both the temps and the percentage load per core in realtime. Then you can begin to understand how much load occurs during specific apps. The only time I approach the loads induced by prime 95 is when I do a render from 3dsmax.

Cheers,
Bob
 

andy5174

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Well related questions! :)

1. Try to reset the HSF and see if you can get these temps closer to one another.

2. Yes. To be safe, you don't want to push it further with your current HSF. Get a Prolimatech Megashadow if you want more aggressive OC.

3. Yes, it is sufficiently good at doing so. However, IBT/Linkpack can push it further according to a few peoples.

4. Yes. However, there are very little applications will make your CPU as hot as under prime95 and those programs are mostly for professional use.

5. No, it will not.

6. Yes.
 

GBleezy

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Hey thanks! All good info to know and take in to consideration!

But check this...after spending all day trying to find the right timmings for my buses, the right volts for my clocks and speeds for my frequencies...I ACTUALLY STUMBLED UPON A VERY WORKABLE SOLUTION FOR MYSELF!!!

I finally just went ahead and I....

1) loaded the default F7:'Fail-Safe' settings in to my CMOS (or bios? or w/e...)
2) Changed XMP from Disabled to Enabled.
3)Fixed Boot Order
4)F10:Save & Reboot


Uhm....Long story short....my Ram went straight to 1057mhz and stayed there. While my CPU stays at a cool 1.8GHz while I'm just chilling. But when it starts poppin' off and crackin' on my desktop...jumps straight up to 4.0GHz and stays there as long as it's needed. Firefox actually crashed on me while viewing a PDF before i started typing this, and that had my CPU pegged at 4.0GHz and I just let it sit there for about 10min while i went to smoke a cig, firefox never recovered, and the whole time the temps never got over 70! Probably more like 65...

Anyways...while i was running some quick benchmarks in everast that i was going to add to this post, i got BSOD :p BUT...i was doing everything BUT benchmarking for at least an hour straight before i got that blue screen!

And I mean we're overclocking here right? But really...we don't need our CPUs idling at 4.0GHz!! I'd rather it just be able to reach that speed when it needs really...I'm wondering now though, that I got this BSOD, what kind of settings were actually changed when I Enabled XMP?? Did it change all my DDR timings? What options did it change that allows it to go from 1.8GHz to 4.0GHz when it needs? EIST? Turbo Boost?

Basically...I loved what happened when I "Enabled" XMP! (Wasn't able to get my RAM up that high before!) But now I need to just tweak from here ya know? I'm thinking if I can't handle a solid benchmark, then maybe i just need to tweak some more...Altho, idk...any longer than 10min at 4.0GHz 100% load...would probably setoff PROCHOT# sig or w/e :p

(LGA1156 Thermal Specs and Design Guide: http://docs.google.com/leaf?id=0B-pZEv4FtGXMNzE1NjVmZmUtYmE3OS00ZWMwLWEzMDUtMmYzNDkyZTExYzZl&sort=name&layout=list&num=50 )
 

ekoostik

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I've got an i7 860 running on a GA-P55M-UD2 board. I've been playing with it since Sept but haven't stepped up the processor speed. Yet. I'd like, for my first stab at it, to see what kind of boost I can get at stock speeds, while keeping HT, Turbo, EIST and sleep states. I have seen reviews mentioning OCs hitting, for example, 3.33GHz on stock voltage. To me that seems like a good initial goal to hit. Nothing over-the-top or terribly risky.

My question is - what do people mean when they say they've OCed at "stock voltages"? Do I need to manually set values (such as CPU Vcore, QPI/Vtt, PCH Core, CPU PLL) to 'stock' levels? Or if I leave them set to Auto and start raising BCLK, will the voltages remain 'at stock'?
 

andy5174

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@GBleezy

What is the sepcification of your RAM?

But really...we don't need our CPUs idling at 4.0GHz!! I'd rather it just be able to reach that speed when it needs really...
Turn on C1E, C3/C6/C7 and EIST.


@ekoostik

what do people mean when they say they've OCed at "stock voltages"?
There is no such thing as stock Vcore, but many peoples refer 1.20V under full load as STOCK Vcore.

The rest voltages(PCH, PLL, Vtt/IMC, Vram) have "Typical" values provided in Intel's datasheet which people refer them as stock voltages.

Do I need to manually set values (such as CPU Vcore, QPI/Vtt, PCH Core, CPU PLL) to 'stock' levels?
You don't have to set the voltages manually with such a mild OC(3.33GHz). However, BIOS will automatically set them to much higher than required values and results in much higher temps.

Or if I leave them set to Auto and start raising BCLK, will the voltages remain 'at stock'?
No.
 
G

Guest

Guest
Have a couple of questions.

I am currently over clocking my i7 860.

Why do we need to turn off hyper-threading and turbo boost?
 

LoneWolf_53

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I don't turn off hyper-threading but I do turbo-boost.

The reason is that as you overclock and push your system beyond it's stock settings you put more demand on the components and have to tinker with it to get it to run stable.

If you leave turbo boost enabled the system gets pushed even harder and generally results in instability.

Better to have settings that remain where you know everything is alright.
 
G

Guest

Guest
But i mean, if i over clock to FCLK of 160x22, the difference between OC with no turbo and stock clock with turbo is minimal.,...is it any point?
 

andy5174

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@sondrol1977

Why do we need to turn off hyper-threading and turbo boost?
You don't have to turn off HT unless it's impossible to get your system stable with it turned ON. It is mentioned in this guide....

But i mean, if i over clock to FCLK of 160x22, the difference between OC with no turbo and stock clock with turbo is minimal.,...is it any point?
160x22 w/o turbo boost will definitely give you better performance than 133x21 with turbo boost most of the time.

p.s. Turbo boost is automatically turned off with 22x multiplier.
 

LoneWolf_53

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Yes the point is for some the difference between running stable and not running stable comes down to whether Turbo Boost is on or not.

In other cases I know people who have had success with Speed Step and Turbo Boost still enabled.

Personal preference perhaps but I also prefer to know my settings are applied equally across all four cores as opposed to Turbo Boost which doesn't really do that.


You might be interested in reading this article.............. http://www.tomshardware.com/reviews/turbo-boost-overclocking,2512.html
 
G

Guest

Guest


That explains the turbo part. But i dont know why it is running at 22x in my case.... I have only changed the FCLK, the multiplier is still auto....so should be 21..... my bios reports that 21 is NO turbo and 22x is turbo.



 

andy5174

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@ sondrol1977

That explains the turbo part. But i dont know why it is running at 22x in my case.... I have only changed the FCLK, the multiplier is still auto....so should be 21..... my bios reports that 21 is NO turbo and 22x is turbo.
You need to turn off the "Turbo Boost" manually in your BIOS.
 

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