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Review final i5 750 OC

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January 26, 2011 9:07:09 AM

BCLK : 166
Ram Multi x8 : 1333mhz
Turbo boost, c1, eist : enabled
CPU VCore : 1.30625 - Normal
Dynamic Vcore : +0.00000v
Qpi/Vtt : 1.21

Results to x21 3,48ghz when 4 cores are active and x24 3,98ghz when 1 or 2 cores are active. Cpu-Z shows 1.280v when running prime95 temps don't go over 51C during the tests. Also it throttles down to 0.8v on idle.

The question is about an article written on Tom's about efficient overclocking with Turbo which suggested that 160 BCLK was the highest and most efficient OC. Am i voiding this efficiency by upping the BCLK to 166? Because the previous overclock i used was the same settings with 160 BCLK and the temps were the same.

Are the temps the only factor for efficiency or the volts pumped in the CPU? Because on 160 BCLK the cpu needed a range from 1.248v to 1.268v and now it hovers in the 1.28 to 1.30 area. Is that a big leap for a near 4ghz overclock?

EDIT : I would like to clear that 1.30625 is the CPU VID it isnt a value i have set in the bios.

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a b K Overclocking
January 26, 2011 1:59:56 PM


The reason for the 160 MHz BCLK is that you can achieve this at stock or a slight increase in voltage (all chips are different).

Are you running with auto setting for Vcore? 1.3 seems rather high with a BCLK of 160.
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January 26, 2011 2:01:58 PM

No the Vcore is set to Normal not Auto, Auto was the default value and i changed it to Normal. 1.30625 is the CPU Vcore that the chip sets to the motherboard (CPU VID)
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January 26, 2011 2:03:29 PM

And don't get it twisted i am shooting for an OC with Turbo on so you must multiply the BCLK x24 for the final OC. So 1.3 isn't an exaggeration for 3,98ghz right?
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a b à CPUs
a b K Overclocking
January 26, 2011 2:10:35 PM

Right, for a ~4 GHz OC it is an OK setting, but you should try and manually dial in the voltages, as that is where the efficiency comes in, the lower voltage you can run it at (stable), the more efficient it is.

Edit: From your original post, no, heat has nothing to do with efficiency, but the more voltage you run through the CPU the more heat will be generated.
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January 26, 2011 5:14:10 PM

Best answer selected by darkling.
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January 27, 2011 5:24:28 AM

Nah, i decided to tone it down to 160 BCLK. It isn't worth the extra effort to run at 166 i mean i get vcore as high as 1.296v running prime while i used to get 1.248 - 1.26. Temps are not my problem i got a hyper 212+ which keeps the cpu at 55C max.
My concern starts on the power consumption and efficieny by this small change.

Maybe i will go back to 160 BCLK and shoot for the lowest voltage possible because my VID is so high i used a negative voffset in the bios, maybe i will increase it to see how low can i go on voltages. I am guessing 1.21 - 1.23 can do 160 with turbo on.

Any opinions on Load Line Calibration? Enable it or not? Mine is at AUTO on a ga-p55-usb3 which i haven't seen what it means.

And one last thing, about the 1.30625v set as default vcore in the bios. Is that set by the CPU so i don't have many choices to run mu CPU on lower volts or is that option set by the motherboard? because when i start fiddling with my PC i used an offset of 0.1v and run my PC at stock settings with 1.18v. So the CPU can run with lower volts.
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