NB Voltage and overclocking to 3.8ghz

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zealengine

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Dec 7, 2009
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I have the following setup...

Asus M4A79XTD MB
AMD PH II X4 955 3.2ghz BE
Sunbeam freezer with AS5
Saphire Radeon 4890
4gb Gskill PC 1600 DDR3
2x 1 TB Seagate HD (Raid 1)
Antec 300 case with extra fans (all air exiting the case is cool)
500w Thermaltake psu

After much research, I have been able to get a stable overclock of 200 x17 (2200 HT, 2200 NB) at 1.4v cpu, 1.175 cpu/nb (stable prime 95 for hours, max load 52c). However, if I push much beyond that, I prime95 usually wont last longer than a few minutes.

My question is - I have read that I should be running between 1.175-1.25v for my cpu/nb, but the problem is my bios has THREE "NB voltage settings", they are...

CPU/NB Volt
NB Volt
NB 1.8 Volt

Assuming I am aiming for a 3.8ghz overclock, can anyone tell me what THOSE THREE voltages should be? I also imagine I might need to bump up my cpu voltage higher than 1.4v, but I have heard people say they get to 3.8 stable at 1.4 by only bumping their NB voltage...

*BTW do my ram settings matter when overclocking? I am currently 1600hz at 1.5v 9-9-9-24 timings.

Thanks in advance!
 
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Try this :

CPU @ 1.39/1.4v
CPU/NB @ 1.25v or 1.3v if you are overclocking your HT clock (FSB)
NB @ 1.38/1.39v

HT Link Speed I would set to 2000 if you are overclocking your HT clock (FSB) if not I would set it to 2200mhz........

Disable CIE, Cool & Quiet, Gart and Advanced Clock Calibration. Leave everything else ENABLED......Leave bank interleaving and channel interleaving at auto....

Play with your voltages till you find a stable system.... hope this helps 😉

Leave your ram alone for now, later on when your system is stable at the desired clock you can play with the ram...
 
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Oh i know, havnt seen him on in months...

im sure things will slow down during the holidays, maybe even enough so that he can grace us with his presence. [:jaydeejohn:4]
 
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Forgot to add that you need to raise the CPU multiplier (frequency) to x19 for 3.8Ghz, this is obvious but I just wanted throw it out there. You can also lower the multi and raise the FSB also, but that can be done later.
 
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Ok I am running a prime95 stress test right now. What I decided to do is get my cpu to 3.8ghz first, then worry about the ht/nb freq and clocks. Will this work? Will I be able to get a stabel system by leaving everythign at defaults, and just raising the cpu multiplier & cpu voltage? Or do I need to riase everything together?

(I kinda want to do it this way so I can find the minimum cpu voltage I need to run at 3.8ghz, since temp is a huge conern for me).
 
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Your temps will be fine, the only way your CPU will overheat is by giving it too much juice when it's not really needed. Try the above settings and work your way down. In the end you will find the exact voltage needed for that specific clock. You can start with 1.35v if you want as well but I cannot guarantee that it will be stable at 3.8Ghz. It all depends if your board likes more/less volts...
 
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Ok when I get to overclocking the nb I will start at your recommended volts and work my way down. In the meantime, I should be ok just working with the cpu multiplier and cpu voltage untill I get stable 3.8ghz (things should be stable even with everything else at defaults right)? THEN I will worry about nb/ht/ram ect...
 
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Not exactly, you want to maintain the NB volts close to the CPU volts, meaning if you have a CPU voltage of 1.38v then your NB voltage should be around the 1.36/1.37/1.38v as well, don't leave your NB on auto after 3.6Ghz...

It is normal to start off with a high voltage rate and gradually go lower until stability is found (at least voltage possible). I do it both ways, depending on CPU....
 
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*mini status update

Prime 95 was crashing in a few minutes at x18 (3600ghz) with cpu 1.4v (everything else at defaults. I tried bumping my cpu/nb volt and nb volt to 1.25 - and I still crashed in about 5min.

HOWEVER, I just tried upping my cpu volt to 1.425, and lowered everything else back to default. Seems much more stable now. Been running prim95 for over 30min no crash (will let it run for another hour or so before I try x18.5). CPU temps max at 50c.

So it seems like my cpu voltage is more important than my cpu/nb voltage for some reason. However I will still try upping cpu/nb as you suggest (now that I am going beyond 3.6ghz).

 
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Your system crashed cause you cannot have the multiplier at x18 and everything else on auto, that is why I told you to keep the CPU and NB volts close to each other for maximum stability.

Here is how I run my x2 550 / x4 B50 :

CPU multi at x17.5
CPU voltage at 1.425
NB at 1.4v
CPU/NB at 1.3v
FSB at 230

Full 24 hour prime stable.....

If you are not going to raise the FSB then leave the CPU/NB on 1.2 (default)
 
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If you are not going to raise the FSB then leave the CPU/NB on 1.2 (default)
Click to expand...

Why would it matter if I modify the fsb or just manipulate the multiplier? I didnt think there was any difference. Besides it was my understanding that these cpus dont even have a fsb - the 'fsb' is really just a number, nothing more, that the cpu multiplier, nb multiplier, ect... use to determine their final frequency. Is that not right?

But I will try lowering my cpu v and upping my cpu/nb and nb volts... cross your fingers...

*btw you want me to leave the nb/ht freq at default for all this right? (default is currently 2000hz for both nb and ht)
 
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Look, there is MUCH more to overclocking than you think... I am giving you an idea of what you can do to get a moderate overclock. There 2 different ways of doing this, you can either raise the multiplier and CPU voltage alone or you can lower the multiplier and raise the FSB (bus). If you decide to raise the bus you will also raise the CPU frequency as well. Some boards and CPU's acquire a stable overclock my just raising the CPU multi only while others love FSB. So it is a matter of you playing around for a few hours till you find the sweet-spot. Nothing is going to happen to the PC as long as you don't overvolt. Here is a very good tutorial that should help you understand more :

http://www.sevenforums.com/hardware-devices/6030-how-am2-am2-am3-phenom-phenomii-overclocking-guide.html
 
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Argg I am just not having any luck raising cpu/nb or nb voltage. It just doesnt seem to matter.

I am currently running 225 x 16.5 (nb and ht running at 2250hz), cpu voltage 1.425, nb/cpu voltage 1.3v, nb volt 1.3v. I can boot to windows just fine, but I crash withing 5 seconds of prime95.

Earlier I tried 200x18 with cpu voltage at 1.4375, and all other options on auto (yes auto), and I was able to run prime 95 for over 30min before a crash. It just feels like the onlything that seems to help is upping my cpu voltage. I am 99% sure if I up my voltage to something like 1.47+ I would be able to run at x18 no problem... im a little worried to go that high though since my temps are already at 52c.
 
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1.47 is way to high for 3.6Ghz. Again, look at your NB, why are you leaving the NB at 1.3v while the CPU is at 1.47? There is way too much of a gap in between..

You should be able to get 3.6Ghz with 1.37/1.38v on the CPU...

Run a stress test at 3.6Ghz and don't give it more than 1.38v on the CPU.

Do you know how to take screenshots?
 
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1.47 is way to high for 3.6Ghz. Again, look at your NB, why are you leaving the NB at 1.3v while the CPU is at 1.47? There is way too much of a gap in between..
Click to expand...

Are you 100% sure the two need to be in lockstep? I mean when you think about it one is running at 3.8ghz, while the other is running at 2.2-2.4ghz, so if the frequencies are that off, why do the voltages need to be 1:1? All the research I have read up to this point suggests a much lower voltage for your cpu/nb...

http://www.ocforums.com/showthread.php?t=621053

http://www.ocforums.com/showthread.php?t=594100

And I cant even run prime95 for 5 seconds at 3.6ghz with my cpu volt at 1.38.

*I just tried 200x18.5 with 1.46v cpu 1.3v cpu/nb all rest on auto (so 2000hz nb and 2000hz ht). I was able to run a torture test for over an hour, but eventually my machine did reset (temps were around 53-54c max). If I lower my cpu volt down to just 1.45 I cant last more than 3 minutes.
 
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You are comparing your Evo vs. a GD70, they are both very different in a way. Not all boards overclock with the same values.

If you look closely at his signature you will see where he is at 3.5Ghz with "stock" volts that means that he is at 1.3/1.32v flat. Looks like your CPU is volt hungry cause like I said 1.47 is almost 1.5v, normally that amount is used for an overclock of 4.2Ghz give or take...
 
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Leave the NB at 1.3v and do this :

AsusOC.jpg
 
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My last oc attempt was almost identical...

(this is EVERY setting in my 'Advanced - JumperFree config' in bios)

cpu bus freq - 200
pcie freq 100

cpu ratio - 18.5
cpu/nb freq - 2400hz
cpu voltage - 1.45v
cpu/nb voltage - 1.3v
cpu vdda volt - AUTO

HT linkspeed - 2200hz
HT linkwidth - AUTO
HT Volt - AUTO

DRAM freq - AUTO (amd overdrive shows 666hz)
DRAM Volt - AUTO (amd overdrive shows 1.6v)
(all timings auto, amd overdrive shows 9-9-9-24)

NB Volt - 1.3v (it turns ORANGE when I set it this high)
NB 1.8v - AUTO
SB Volt - AUTO (amd overdrive shows 1.35v, which is max... odd)

Booted into windows just fine (have yet to have trouble booting into windows). Ran prime95 torture test, lasted about 3min, only got up to 52c, then screen went black, and auto reset.

So unless INCREASING my cpu bus freq from 200 to 205 and/or increasing my multiplier to 19 will make things MORE stable (dont see how that is possible), your suggested settings wont work either. I will still try them if you want though...

*I really appreciate all your help btw!
 
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yea my bad, I was confusing my Asrock Bios with My Asus Bios.... You were right and I was wrong about the NB volts. The thing is that one of my boards has an Nvidia chipset and you have to raise the NB volts pretty high to get a stable clock, that is not the case with the Asus.....
 
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Hrmm well I rolled back to the following...

cpu bus freq - 200
pcie freq 100

cpu ratio - 18.0
cpu/nb freq - 2400hz
cpu voltage - 1.45v
cpu/nb voltage - 1.25v
cpu vdda volt - AUTO

HT linkspeed - 2200hz
HT linkwidth - AUTO
HT Volt - AUTO

DRAM freq - AUTO (amd overdrive shows 666hz)
DRAM Volt - AUTO (amd overdrive shows 1.6v)
(all timings auto, amd overdrive shows 9-9-9-24)

NB Volt - AUTO (amd overdrive shows 1.1v)
NB 1.8v - AUTO
SB Volt - AUTO (amd overdrive shows 1.35v, which is max... odd)

Been running prime95 for 3-4 hours, solid as a rock (53c max).

But I really want to hit 3.8ghz... any ideas? Should I just keep upping my cpu voltage? Or is there something else I could try.
 
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