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OC BCLK to 100 MHz even after CPU overclock

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July 10, 2014 3:15:55 PM

After OCing the CPU (i7-4770K) even only to 4,1GHz the BCLK diminishes to 99.98, on a G1 Sniper M5.

I don't want to have less bandwidth (even if it's only 0,5%, as OC is free) so I OCed it to 102 MHz, but the computer became unstable, the CPU refused to pass x38 multiplier (as reported by CPU-Z)
and the Super Pi 32M test lasted 7 minutes more than with the old BCLK frequency.

I supposed it needed more voltaje, so I put +0.05V and +0,3V in the 2 chipset related voltajes (I don't know what they were, but in the BIOS it said explicitly they were related to the chipset) and the results were the same.

Finally I increased voltajes a bit more, and also +0.05 to CPU, and +0.1 to RAM and GPU, but the computer didn't boot after that.

I pressed the Clear CMOS button and now I have 99.76 MHz BCLK. Is it telling me that I'm a noob? How I can get back at least a 100 MHz one, or even better a slightly better one at 100.5?
a b K Overclocking
a b à CPUs
July 10, 2014 3:21:49 PM

If CPU-Z is telling you this then it is normal. There is something in the code which will report a lower BCLK than its actual values.
You shouldn't really overclock the BCLK really for a cpu overclock.
Also you won;t notice any perofrmance decrease from a 0.02 MhZ difference anyway.
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a b K Overclocking
a b à CPUs
July 10, 2014 3:38:26 PM

On i7 4770K you simply do not touch the BCLK. It is tied to every component you have - PCIe slots, Sata, RAM - everything. The BCLK you are seeing is because of Spread Spectrum. It varies the BCLK between 99.8 and 100 to reduce electromagnetic emissions than can be very bad in laboratory conditions for example. Just set the BCLK to 100 and OC as much as you can with the multiplier. If you set a BCLK of, lets say, 102 MHz, it might slowly degrade your components and even kill them and/or your motherboard. BCLK on Sandy Bridge, Ivy Bridge, Haswell is meant to be 100 and that's all there is to it.

P.S disable Spread Spectrum from the BIOS to get 100 BCLK constantly.
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July 10, 2014 3:52:20 PM

Thank you Suztera. Does it exist any software to monitor frequencies and that stuff with accuracy?

And why couldn't I OC the BCLK just 2MHz, even with higher voltages? By the way, temps didn't exceed 40ºC even in the CPU, that's not the problem.
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a b K Overclocking
a b à CPUs
July 10, 2014 3:58:16 PM

As Shneiky, overclocking BCLK will increase the speed of other components. It increase the chance of data corruption and instability. For cpu overclocking, it better to do it via the cpu multiplier ratio /turbo boost ratio.
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a b K Overclocking
a b à CPUs
July 10, 2014 4:00:15 PM

Because BCLK is not ment to be overclocked on a Haswell system. In the old Core2Duo, you had FSB and you could play with both the FSB (something like a BCLK) and the Multiplier. BCLK different than 99 - 100 MHz can easily lead to system instabilities - regardless of voltage or temperature. Imagine it like someone is messing with your brain and making your speech, motor functions and thinking run out of synch. That is what BCLK OC can do.
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July 11, 2014 8:10:59 AM

So, in conclusion, the BCLK must be 100, I suppose more is only useful to achieve that very unstable world records.
Thank you.



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