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M3A78

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June 30, 2009 5:39:11 PM

Hello- I have the ASUS M3A78 motherboard- and can't find an option to change the North Bridge multiplier anywhere in the Bios. My CPU is a Phenom 940 Black Edition. The option simply isn't there, and I think I need to if I want to overclock more. My next two upgrades might be a Monitor and Water Cooling solution, but I don't know. If I can't find an option in the bios, I might get a new motherboard- but I would prefer not doing that.

Thanks a ton guys for any help you can give me on this matter. I'm not sure if I'm being bottlenecked, but I might be.

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June 30, 2009 8:47:42 PM

I do not see AI overclocking as one of the options on my Motherboard.
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June 30, 2009 9:32:59 PM

Just checked the manual for that 770 mobo and it looks like the option is not there. Luckily with a black edition processor you should not need to touch (lower) the NB frequency to push the CPU frequency near it's max.

How high have you been able to OC the CPU sticking to multiplier overclocking?

How high a reference clock and NB frequency have you reached? (CPU-Z will tell you).



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June 30, 2009 9:41:12 PM

The CPU has reached 3.4 GHz with complete stability and 3.5Ghz with iffy stability (Ocassional BSODs). This is a multiplier of 17 and 17.5. I can get to 4 Ghz, but it will not boot into windows (big surprise).

The highest reference clock I have gotten was 280. The North Bridge Frequency therefore would be at 2520 (Didn't need to check CPU-Z for that, just used a calculator).

Thanks for your help so far! :) 
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June 30, 2009 10:18:23 PM

280 ref clock is excellent. Out of curiosity, what CPU-NB voltage did that take?

What cooler? What are the CPU temps? What CPU voltage are you running at 3.5GHz? Sorry for so many questions, but these are main reasons for losing stability (too high temps or too little voltage)

Have you disabled Cool 'n' Quiet, C1e, SB Spread Spectrum?
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July 1, 2009 4:17:09 AM

Spread Spectrum isn't on my bios for some reason.

All else is off.

CPU-NB voltage was +50mv (whatever that increase is).

Currently Stock CPU Cooler- which is pretty good- though I want a better one some time- I need a job.

CPU Voltage at 3.5ghz is +150mv.

Temperature at 3.5ghz is 55 degrees C at Idle, goes up to 75 during extreme load- I don't trust those readings though, at 70 Degrees C, the computer should shut down- I'm reaching a temperature that will cause water to evaporate.
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July 2, 2009 11:30:51 AM

The PII's I have used needed 1.375V - 1.400V to reach stability at 3.5GHz. You may be feeding yours 1.5V...more than needed and too much for the stock cooler.

Your temps (if accurate) are very high. And if you are using 1.5V with the stock cooler they may just be spot on and you are at risk of component damage.

It would be good to know exactly what voltage is being supplied to the CPU. Did you work up to that in 25-50 mV steps, or just jump straight to +150mV? Extra voltage will generate excess heat and you only want to use as much as you need for stability.

My suggestion is download the latest version of AMD's Overdrive. It's quite handy for overclocking. But even if you do not use it to overclock, you'll see a wealth of info like temps and voltages. Leave your system OC'ed from the BIOS and see what the CPU VID is listed at in AOD. You can even lower it/raise it right from there and stress test it without rebooting. Not sure if you read the OC Guide linked above, but I highlighted in depth how to OC with AOD.



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July 2, 2009 2:25:10 PM

Thank you.


I am only interested in overclocking the northbridge because I read that it can increase performance.


Anyway, You are right- I'm going to lower my voltages some. CPU-Z says I'm at 1.456 volts, while AMD overdrive states my voltages are at 1.275

I'm going to try 50 mV. If that works fine, I'll try default.
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July 2, 2009 4:14:33 PM

+50 mV works fine.

Temps at idle are now at 50c. I'm going to try to increase the fan speed on the cooler.
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July 3, 2009 4:20:39 AM

Anything less than 1.456 was unstable in a quick Prime 95 Test.

I did however, manage to get the North Bridge higher, by increasing the Bus Speed to 260. It failed Prime 95 instantly, and it caused my RAM to be... strange.

I might try again tomorrow at a bus speed of 250 and see if I can avoid increasing the voltage.
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July 13, 2009 12:37:58 AM

250 worked fine, thanks guys. Topic is now closed as solved :) 
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