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Intel Core-i3/i5/i7 LGA1156 Overclocking Guide E-mail
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Written by Servando Silva   
Tuesday, 24 August 2010
Table of Contents: Page Index
Intel Core-i3/i5/i7 LGA1156 Overclocking Guide
Why Should I Overclock?
Overclocking Applications and Utilities
Processor Stability Testing
Understanding OC Variables
OC Testing Methodology
Overclocking Frequency vs. Voltage
Overclock vs Power Consumption
Overclock vs Temperatures
Final Thoughts

Overclock Testing Methodology

Let's start overclocking our LGA 1156 setup. First thing you might want to do is start overclocking your CPU. Since it's working at stock speeds with stock voltages, you might have a good gap to increase MHz before reaching its voltage limits. That might be the easiest step since your RAM or motherboard shouldn't be limiting to achieve it. But you should really start isolating CPU from all other components. For example, if your memory works at 1333MHz by default, try lowering memory multiplier to 1066MHz. Since you'll need to increase BCLK to increase CPU frequency, all other components related to BCLK will increase their value, and RAM memory could be limiting you.

In other cases, I'd also recommend lowering CPU multiplier and find you maximum BCLK if possible. Plan a target and try to find it depending on what you're expecting to reach. For example, let's say you want to reach 4GHz with a 20x multiplier. That means you need 200BCLK x 20 CPU multi = 4000MHz. Lower your RAM and CPU multipliers to the lowest possible setting and start increasing BCLK to reach 200MHz. If you're lucky enough, you will achieve 200MHz and then you'll know your motherboard won't be an issue. If you start raising your CPU along with the motherboard, you might hit a wall where you won't know if the problem relies on CPU or motherboard. Now imagine you also overclock your memory at the same time, and you'll end with a headache stopping you from trying and testing.


Once you've tested your motherboard, now it's time to increase your CPU frequency. Enter to your BIOS and set your CPU multiplier back to where it was initially and start increasing BCLK in 5MHz steps. Since many CPU multipliers will start at 20x or similar, each 5 BCLK MHz you'll be adding a total of 100MHz to CPU's frequency. Every time you add 5 MHz to the BCLK, you'll need to enter your OS and start doing stability tests as explained in the latest pages. If you think it is safe enough, you could try adding 10-15MHz to BCLK at the beginning, but eventually, you'll end adding 3-5MHz.

You'll end topping a wall where you won't be able to get a stable CPU. It's important to make BCLK increases in small steps, because your PC will be able to BOOT and it might enter to Windows, or at least you'll be able to change BIOS settings again to reduce values. If you do big BCLK increases, chances that you end with a PC not being able to POST are high, and you'll need to press the reset switch/jumper and start setting all things again. This can be very complicated if your motherboard is inside a small case, and unless you're able to save BIOS profiles, you'll need to remember and set all the parameters again.

Finally, after you've reached your maximum frequency, you might want to start adding vCore in 25mV steps (depending on your cooling) until you reach a stable frequency again. The process gets repeated until you've reached your maximum CPU frequency with the voltage desired. Keep an eye on temperatures while doing stability tests, as that should be a limiting for you depending on your setup.

Finally, it's time to overclock your memory and see what it can do. You'll need to save your CPU settings (or remember them) and lower the CPU multiplier again to isolate memory frequency from CPU frequency. Start doing the same process you've done with the CPU, but now with the memory until you reach a maximum frequency at a rated voltage and there you go. Now you'll need to find a balance between your maximum memory frequency and maximum CPU frequency. Let me tell you CPU frequency gives much more boost than memory frequency, so, CPU will always have higher priority in your balace's list. If, and only if you're reaching high BCLK MHz, you should start raising QPI/VTT/IMC voltage. But that won't be needed if you already tested your BCLK before starting with CPU and RAM frequencies. All other voltage values could be left on auto-mode and they might not be necessary to achieve what you want.

What if I'm "overclarking" my Core i3/i5? If you're overclocking your Core i3/i5 processor, you'll need to keep an eye on an extra variable: iGPU frequency. Unless you're using a dedicated GPU, you'll be using Intel GMA HD integrated graphics on CPU die. Of course, this parameter can also be overclocked (a lot, by the way), but you'll need to check it randomly to see if it's not limiting your CPU overclock. There are some motherboards where you can NOT detach iGPU from BCLK, and that's bad because your CPU frequency will be limited by your maximum iGPU frequency. Luckily, many motherboards have this option already unlinked or at least, they give you an option to unlink it so you can overclock your CPU without modifying iGPU frequency. Again, I repeat: If you're using a discrete graphics card (PCI-e slots), Intel GMA HD graphics unit should be disabled and the whole process will be easier (CPU could overclock higher).

Intel P55 Test Platform

  • Processor: 3.2GHz Intel Core i5 655K Unlocked CPU
  • Processor: 2.9GHz Intel Core i3 530 CPU
  • Processor: 2.8GHz Intel Core i7 860 CPU
  • CPU Heatsink: Noctua NH-D14 with NF-P14 fans
  • Motherboard: ASUS Maximus III Formula P55 Motherboard
  • System Memory: 2x2GB G.Skill ECO Series DDR3 (1333MHz @ 7-7-7-20)
  • Video: Powercolor ATI Radeon HD 5850 1GB
  • Disk Drive 1: Intel X-25M 80GB SSD
  • Disk Drive 2: SEAGATE Barracuda 1TB SATA
  • PSU: Antec Signature 850W
  • Operating System: Windows 7 Ultimate x64

Applications & Utilities

  • Memtest 4.0
  • OCCT Perestroika 3.0.1
  • ASUS Turbo V
  • Real Temp
  • Prime95 - Blend Test
  • CPU Tweaker



# Wow!fr0hzn 2010-08-25 05:00
I just bought an i5 recently and I have to say that I will definately try to overclock it, after I've read here what I can achieve :)
Very informative, thank you!
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# Glad to help.Servando Silva 2010-08-25 17:18
That's great. Post your questions/results in our forums!
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# Great InformationGorham4 2010-08-25 07:48
Very nice article full of great basic information. For those interested there are numerous groups that hold overclocking competitions. If you do a google on Forum Wars it will lead you to some interesting forums where you can gain additional knowledge and try you hand at basic and advanced overclocking with supportive groups.

Again thanks for a great article on what should be every computer owner's for activity when buying or building a new computer.
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# Nice work, but would have been great with benefits (or not)baldheadeddork 2010-08-26 16:59
Really nice comparison between the dual and quad core i-Series, but what's the payoff in applications? If you can make a second part showing these three in game performance and media encoding - that would bring it home.

It would also be interesting to see how the dual cores compare to the quads.
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# RE: Intel Core-i3/i5/i7 LGA1156 Overclocking GuideServando Silva 2010-08-26 17:39
As I've said in the article, I was focusing on how to overclock and variables involved. Perhaps, this review could help you make a decision:
I'll consider doing a second part focusing on performance though...
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# Very helpful guide!ulsar 2010-10-08 11:20
Great article for those newbies (and not so newbies) in this matter, like myself. I've got an i5 750 on a P7P55D EVO for about two months and it's time to enhance its performance a bit, so this guide will be really helpful.

Thanks a lot!
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# p55-usb3christian 2011-12-20 04:55
hi, i have p55-usb3 motherbord, but the same fan and a i7-860 cpu, i hope can use this great article anyway?
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# i3 330MChristian Conefery 2011-12-26 17:08
Is This possible with i3 330M or is it not powerful enough
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