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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 vs Power Consumption

Some people cry a lot about power consumption (including me). I'm the kind of person who wants the best efficiency if possible, and that means I want my CPU as fast as I can without doubling power consumption. As if we didn't had enough with all the extra components already! Reality is, many people don't even bother about power consumption, and after all, that's why they paid for 800 watts PSU (even if they normally don't use more than 300 watts). Anyway, I'll test both Idle and Prime 95 modes and measure overall PC power consumption with a p3 international kill-a-watt meter. Have a look at the next results as they represent power consumption (without monitor or external peripherals) in idle mode. This numbers are important as you probably keep your PC near idle mode 70% (or more) of your time.

LGA1156_Overclocking_CPU_Power_vs_Voltage_Idle.png

As you can see, power consumption increases a little when you overclock with stock voltage. Maximum difference was 6 watts represented by the Core i7 860, while the Core i3 and Core i5 processors only increased 2-4 watts in idle mode. A 3% increment in idle mode compared to the 25-30% increase in MHz makes this look as the highest efficiency setup of all them. Anyway, we can only make conclusions after analyzing Full Load results, but I hope they won't increase that much. Increasing CPU vCore to 1.3v still adds a little percentage to the power consumption; however, the slope inclines a lot more when going to 1.5 volts as you can see in the chart. Now, let's have a look at Full Load (Prime95 Blend Test) results:

LGA1156_Overclocking_CPU_Power_vs_Voltage_Prime95.png

Ok, now we're talking... The Core i7 860 quickly reached 180 watts at full load, against 125-133 watts at load for the rest of the CPUs. Overclocking with stock voltage increased 3-4 watts on Clarkdale's processors while it increased 10 watts for the Lynnfield's CPU. In this case, the slope becomes bigger at 1.3v, especially the Core i7 860 which already passed 205 watts. The Core i3 is still doing fine with 10 extra watts over stock frequencies, and the Core i5 655K is consuming 15 extra watts compared to stock frequencies. I think it would be wise to say 1.3v is the maximum vCore accepted to keep efficient results at the end. Notice how the slope inclines a lot more with 1.4v and 1.5v? Those results make overall efficiency go down and you shouldn't apply it unless you don't care about power consumption or you're aiming for benchmark results only.

Of course, increasing power consumption means the CPU heatsink will have more watts to dissipate, thus increasing CPU temperatures. Let's have a look at our voltage vs. temperature results in the next page then.



 

Comments 

 
# 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: #benchmarkreviews.com/index.php?option=com_content&task=view&id=578&Itemid=63
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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