LGA 1156 Core i7 & i5 Overclocking Guide

[andy5174]

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!

 

[Guest]

Tried that, and multiplier is now at 21.

 

[jsc]

@ jsc:
I think the ONLY useful part to a pro like you is the first QUOTE of 3) Voltages tweaking

Oh, no. My latest experience has been with Core2 CPU's. Haven't upgraded because my OC'd Q9550 is still serving all my purposes.

Not a pro - at least in this area of electronics. Just an amateur who has been doing this for awhile.

BTW, I do not miss the old days. Overclocking with BIOS settings is much easier than cutting PCB traces and running jumpers.

 

[AMW1011]

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??

Intel Burn Test, which is an easy to use skin for Linpack, will hike those temps up there. With it, at 4.0 GHz 1.4v, my i5 750 hits 71 on one core and 69 on all the other. With Prime95 no core goes over 68-69.

I'm using an Xigmatek HDT-s1283 with a Scythe Slipstream 110 CFM 1900RPM fan all in a case that cools like an Antec 900. Your heatsink should be pretty close in performance to mine, try reseating or buy a new fan. The best fans to put on heatsinks are fans with the high CFM and low RPM ratings, because if the RPMs are too high it will cause turbulence between the fins of the heatsink and wont perform well.

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 😛 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 😛

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

I hate to say it but your problems sound like the typical symptoms of unstable RAM. Try running some SuperPI with highest memory value and then some Prime95 blend tests. A general rule is if your RAM's voltage isn't at 1.65v then you should increase the volts a little when changing the settings. For example, my RAM is the Crucial 2x2GB 1333MHz cas 9 RAM at 1.5v. I have it at 1200 MHz 7-7-7-16 timings at 1.6v. Just don't go over a 0.1v increase (EX. 1.5v-1.6v) or 1.65v in general.

Your computer should NOT reach 65c reading a PDF, mine never goes over the mid 50s without doing something intensive, gaming doesn't count.

 

[steadly2004]

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?

I just started, but when I turned off hyper-threading, my temps dropped like 10*, I was hitting 70* with prime95, now I'm only hitting 60-61*. Both situations with 160x22=3.5ghz and a voltage of 1.23. I'm not sure if I could get away with a lower voltage, this is just where the auto settings kept it at, so I locked it in place.

 

[steadly2004]

I thought I'd post up my current overclock which is working just fine. CPU = i7 860 Mobo = ASUS P7P55d-e

Core V- 1.22
freq = 171 x 22

hyperthreading = disabled
turbo = enabled (although it doesn't surpass 22x anyway)

temps are hitting 61-62* with prime 95, ran for only 5 hours or so but had no errors with small or large tests

memory = 856 mhz (1712mhz) at 1.65v timing 8-8-8-24

QPI @ 2741 (5482)

All other voltages are left @ auto, I think the stepping is on, it does drop the multiplier down to 9x at idle.

 

[steadly2004]

***, how come we can't edit our own posts?

*note* I have to take that back, it threw an error on one of the threads after like 8 hours with the blend on prime95, but it might have been from the memory, I don't know damn it.

 

[axisof3vil]

how come every one has a 750?? i have 650, can i still overclock that as easily? =)

 

[andy5174]

how come every one has a 750?? i have 650, can i still overclock that as easily? =)

i5-650 is actually much better in OCing thanks to its 32nm architecture.

Just follow all the instructions in this guide IGNORING the settings and voltage provided as they are for quad core LGA1156 i5-750.

 

[EXT64]

Very informative post andy.

I just wanted to add my experiences to the list. First note, the prime tests are still in progress, so these could change.

3.6GHz (180x20, Turbo OFF)
Load-Line Calibration: Enabled
Vcore= 1.175V (Stock was around 1.15 I think)
QPI/Vtt/IMC= 1.1V (Stock)
PCH= 1.05V (Stock)
PLL= 1.80V (Stock)
RAM= 1.5 (1.54)

I wanted a high stock volts OC. Ironically, the hardest part was fining out what my "Stock Volts" was!

What made it even more confusing was VDroop. Technically, the BIOS said stock was 1.15 ish. But under prime95 load, CPU-Z claimed 1.08 ish! Additionally, I guess since I had volts on auto, it would go up to 1.2V when single/dual thread turbo kicked in.

So, first I tried 1.2 and the above speed. No problem. Then I tried 1.175. Good so far and temps dropped a couple degrees C. Right now it idles in the high 20's to very low 30's C and under Prime95 load (OCCT/Linpack would be 2-4 C higher) the hottest core gets to 54 C (the rest are 52-53 C). At stock (2.8GHz) it would max a hair over 40C, so 10-12 C for an 800MHz OC! And that is even with the auto fan profile, so my 212+'s single fan is only at (a very quiet) 1850RPM.

 

[wolfram23]

I have a question about BCLK. Is it not useful to crank it as much as possible? For instance set it to 400 with an 8 or 9 multiplier (3.2/3.6ghz)? Then set the RAM multiplier to 4 for 1600mhz. My MSI P55GD65 mobo has the OC Genie button and sets it to something like 190 BCLK and x17 multiplier (3.3ghz) with the standard 1600/8-8-8-24 RAM settings.

Right now tho I'm running all stock except the BCLK is at 160 but I have turbo boost and CEIST and all that stuff on as per stock set up. (i5 750 CPU, Patriot Viper II Sector 5 RAM)

Basically I'm looking to OC to around 3.5ghz give or take, ideally optimized to work with an OCed Radeon 5850 (still working on OCing that...)

 

[EXT64]

Well, that would crank the uncore clock up really high (as you can't control the multi on that) which may require more vcore.

 

[wolfram23]

Interesting... I read that high BCLK does indeed suck up a bit more voltage therefore higher temps, but performance can be better at times.

Anyway, have a question: How does QPI affect the PC's speed? I've seen little to no mention about it in overclocking guides other than "Hey, it's there!"

Also, something that seems obvious but I've not seen explicitely stated is concerning a bad OC. Should it crash your system at boot up? Does windows load and crash (I've had that which was a headache as it tried to "repair" for 10 mins before saying it couldn't, and then loading just fine...)?

 

[EXT64]

Well, it is really beyond your chip's abilities if it crashes on startup, to try to avoid this, you can increase in small increments the bclk, then test with prime95, repeat...

For example, I did a bclk of 160, then 170, then finally stopping on 180 with short tests between each. If you really OC too much, the computer will not even POST.

As for QPI, I'm not sure that is really a bottleneck. The uncore speed is however, as it is lower on the i5 than it is on its i7 brethren. So a high bclk certainly will speed up your system, though I see little reason to raise it alone (might as well up the core at the same time).

 

[andy5174]

Very informative post andy.

I just wanted to add my experiences to the list. First note, the prime tests are still in progress, so these could change.

3.6GHz (180x20, Turbo OFF)
Load-Line Calibration: Enabled
Vcore= 1.175V (Stock was around 1.15 I think)
QPI/Vtt/IMC= 1.1V (Stock)
PCH= 1.05V (Stock)
PLL= 1.80V (Stock)
RAM= 1.5 (1.54)

I wanted a high stock volts OC. Ironically, the hardest part was fining out what my "Stock Volts" was!

What made it even more confusing was VDroop. Technically, the BIOS said stock was 1.15 ish. But under prime95 load, CPU-Z claimed 1.08 ish! Additionally, I guess since I had volts on auto, it would go up to 1.2V when single/dual thread turbo kicked in.

So, first I tried 1.2 and the above speed. No problem. Then I tried 1.175. Good so far and temps dropped a couple degrees C. Right now it idles in the high 20's to very low 30's C and under Prime95 load (OCCT/Linpack would be 2-4 C higher) the hottest core gets to 54 C (the rest are 52-53 C). At stock (2.8GHz) it would max a hair over 40C, so 10-12 C for an 800MHz OC! And that is even with the auto fan profile, so my 212+'s single fan is only at (a very quiet) 1850RPM.

WOW, all your voltages are impressive! Which BIOS version are you using?

 

[EXT64]

F8. I tried turning on turbo just for fun (would have been 3.8ish) and it bluescreened on startup, so there is a limit on this chip's stock volt's OCing :lol: .

It passed my fairly short prime run, but has been working great in various games and benches over the past few days. I'd never have imagined getting 3.6 on this low of temps. Now I need to run another power consumption test to see what negative effects this OC had.

 

[wolfram23]

Hey I have a question concerning setting voltages. I thought that a good method for figuring out which needs to be increased is to turn up the other ones a little more than necessary (but within safety) and then tweak the low one until stable. I was running a 200bclk x18 (3.6ghz) last night with Prime95. At the low end of 1.11V core I was getting a couple of errors, it was reduced to one at around 1.17V but even up to about 1.2V I'm still getting an error in one core (not necessarily the same one every time). I have VTT up to 1.2V and PLL up at 2V IIRC, so presumeably they shouldn't be much of an issue... unless overvolting also screws it up? I do notice the temps are a bit higher because of these higher voltages but still not over low 80s in Prime95 (verses high 70s with lower VTT and PLL).

Or should I leave VTT and PLL on AUTO until I figure out the proper core voltage? I was playing with it for maybe an hour and a half so I still have plenty of stuff to try but a little help would be appreciated.

 

[EXT64]

Why the high bclk? Have you tried 20x180?

 

[wolfram23]

Well just to see, but right now it seems stable at 160x21 (turbo off). I ran some short Prime95s without errors. Although with Blend tests, I was getting my temps going up a fair bit, even into the 80s. I still have VTT and PLL on auto tho I really haven't had the chance to optimize them yet so that might be the problem. I finally have a free night to spend some hours on it so hopefully I can get it running cooler. I'm a bit worried I might have to remount the aftermarket cooler I have, because I've never done it before (I got it mounted at the store when I bought it). They might have used too much paste or done something else.

 

[EXT64]

Which cooler do you have? If you have exposed heatpipes, there is a different method. Also, you have an 860, right?

Well, I ran my power tests and was quite pleased. Even when overclocked (with all power saving enabled and turbo off) the idle power was Identical to unOC'ed. I was worried it would go up a little since the chip no longer downclocked, however that was not the case. Watching TV consumed 3 more watts than before, and OCCT Linpack 52W more. Here are the full #'s:

Stock/3.6GHz : All in Watts

Boot: 130/150
Idle: 82-87/82-87
TV: 97/100
LinPack: 170/222

Max temp in Linpack: one core got up to 57C, rest 55-53C.

 

[wolfram23]

For a cooler I'm using the Zalman CNPS 10X Extreme.

My idle tems are in the low 40s maybe high 30s. Power usage tho is only like 11W, although at one point it actually was idling at -0.44W (it's a powerplant now!). Pretty odd. If by 860 you mean my CPU, I'm actually using the same i5 750 as you but a different mobo, the MSI P55GD65. I assume you ask because of the x21 multiplier, but I guess this mobo lets me use it (CPU-Z shows it at that while running too). I'm hoping my higher temps are just because currently VTT and PLL are on auto, so it might be going higher than necessary. I'll try figuring it out tonight.

 

[andy5174]

F8. I tried turning on turbo just for fun (would have been 3.8ish) and it bluescreened on startup, so there is a limit on this chip's stock volt's OCing :lol: .

It passed my fairly short prime run, but has been working great in various games and benches over the past few days. I'd never have imagined getting 3.6 on this low of temps. Now I need to run another power consumption test to see what negative effects this OC had.

I envy you. BSOD for sure with 1.10Vtt and BIOS F5 on my PC. 🙁

However, my pc can also pass short run of prime95 Large/Small FFT test easily with approximately the same PCH and Vcore as you and BIOS F5. How short do you mean by "fairly short prime run" and which Prime test did you use? Thanks.

 

[EXT64]

I can use 21 as well, but it secretly turns on turbo (21 is a turbo multi)

I think it was large, but only a couple hours. I'll try to do more tomorrow just to see how stable (or unstable) this really is.

Would you recommend running large or small FFT?

 

[andy5174]

I can use 21 as well, but it secretly turns on turbo (21 is a turbo multi)

I think it was large, but only a couple hours. I'll try to do more tomorrow just to see how stable (or unstable) this really is.

Would you recommend running large or small FFT?

I recommend Large FFT test although Small FFT is said to be a good measurement of CPU stability, because I had experience in failing Large FFT due to insufficient Vcore (which implies unstable CPU) after passing 24 hours Small FFT test.

By the way, I passed more than 30 hours Large FFT test with the following settings.

3.6GHz:
Load-Line Calibration: Enabled (or Level2 for Gigabyte GA-P55A-UD5)
Vcore= 1.21875V(set in BIOS), 1.20V(shown in CPU-Z)
QPI/Vtt/IMC= 1.14V
PCH= 1.10V
PLL= 1.80V

 

[EXT64]

Alright, I'll try to get in a good run tomorrow on large. However, I doubt it will be 24 hours (I don't need that much stability :lol: )

 

[andy5174]

Otherwise, you can also try LinX which is said to be much better than Prime95 by many experienced PC builders in Anandtech and TOM forum. By the way, 25 runs(default) in LinX takes approximately 40~50 minutes and hence choose the number of runs accordingly. For example, you should choose 75 runs if you want to do a 2-hour LinX test .