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Old 07-02-2009, 12:07 PM   #1
iSeven
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What is 'CPU NB VID' Voltage?

I've currently been overclocking a Gigabyte MA790X board, and so far there is one main question which I am trying to get to the bottom of.

What is the 'CPU NB VID' voltage?

Of course there is the 'NB voltage', and 'CPU voltage', but I can't figure out what this third "hybrid" setting has an effect on.

Anyone who knows this answer and can provide better description, is there any general guidelines to follow when it comes to adjustment for the VID setting? For instance, should my CPU NB VID voltage be set parallel with my CPU core voltage? So far the only noticeable difference I am noticing by upping the NB VID along with the vCore is additional heat. I haven't been able to find any sort of performance or stability related gains from doing this.

I emailed Gigabyte, and the response I got from them is that increasing the voltage of this setting makes the OC settings more stable. OK, that is as generic of an answer as they come, but doesn't actually tell me anything about what it is or really does.

To squeeze some more of my questioning into the same thread--why do HT Link speeds need to be reduced quite a bit to achieve stability when clock frequencies reach high amounts? Can anyone explain the technical reasons behind this? Can someone explain the differences between the HT Link and the NB?

Sorry about so many questions, but I would really like to fully understand the AMD board archetecture.

Thanks
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Old 07-02-2009, 12:33 PM   #2
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Quote:
Originally Posted by iSeven View Post
I've currently been overclocking a Gigabyte MA790X board, and so far there is one main question which I am trying to get to the bottom of.

What is the 'CPU NB VID' voltage?

Of course there is the 'NB voltage', and 'CPU voltage', but I can't figure out what this third "hybrid" setting has an effect on.

Anyone who knows this answer and can provide better description, is there any general guidelines to follow when it comes to adjustment for the VID setting? For instance, should my CPU NB VID voltage be set parallel with my CPU core voltage? So far the only noticeable difference I am noticing by upping the NB VID along with the vCore is additional heat. I haven't been able to find any sort of performance or stability related gains from doing this.

I emailed Gigabyte, and the response I got from them is that increasing the voltage of this setting makes the OC settings more stable. OK, that is as generic of an answer as they come, but doesn't actually tell me anything about what it is or really does.

To squeeze some more of my questioning into the same thread--why do HT Link speeds need to be reduced quite a bit to achieve stability when clock frequencies reach high amounts? Can anyone explain the technical reasons behind this? Can someone explain the differences between the HT Link and the NB?

Sorry about so many questions, but I would really like to fully understand the AMD board archetecture.

Thanks
One NB voltage you'll see is the HT link voltage. The other voltage is the actual NB core voltage. And Also PCI-E voltage, which is also linked to the NB. That's the three voltages. The NB Vid should be the core voltage of the NB. If you raise HT/NB link voltage you may see an increase in cpu temps. This also might happen when you OC and over volt the HT/NB link to the Cpu as well.

Generally speaking raising voltage does help stability. Depending on what you are over clocking and when the voltage is actually necc, will determine how stability goes. Most people get unstable from OCing the cpu ht and NB. So adding voltage to all of it doesn't hurt any thing except you temps.
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Old 07-02-2009, 01:27 PM   #3
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Basically, the higher you push your FSB the higher this CPU NB VID needs to go. I think to get to 260 I needed to add +0.100V to it, but I'm not 100% sure. It's really not important if you have a BE chip.

EDIT: It is important if you do have a BE chip, because the CPU NB has a separate multiplier. If you increase that, you may need to add voltage to the CPU NB VID. Just wanted to be clear.

Last edited by ELItheICEman : 07-21-2009 at 01:04 PM.
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Old 07-02-2009, 08:02 PM   #4
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hhmmmm... my "assumption" was the the cpu/nb voltage, as it is labeled on my AMI bios, has to do with the on-board memory controller, a function that used to be accomplished by the actual northbridge.
so, when i am actually increasing the NB multi, i am overclocking the memory controller. if i turn down my nb overclock, i don't need quite as much cpu/nb to achieve stability. and i have had to apply it regardless of the FSB. pretty sure it has nothing to do with that.

and i personally no longer have the nb-pcie voltage setting, which i remember from so long ago on my m3a-32mvp. now i have nb voltage, and nb 1.8 voltage. i am sure one is pcie, but, of course, the asus manual goes sooo in depth.
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Old 07-02-2009, 10:40 PM   #5
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Yep, cpu/nb vid is the voltage to the IMC in the cpu. nb is on the mobo.
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Old 07-04-2009, 05:47 PM   #6
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I have my CPU/NB up to 2.73Ghz atm but I have taken it ti 2.98Ghz before it doesn't Post.

For 2.73Ghz I had the CPU/NB VID to 1.4v and for 2.8Ghz had it to 1.45v, for 2.9Ghz+ I had from 1.4875v to 1.55v I know it's pushing it but Oh well.

Just a little guide their.

And the Hypertransport Voltage is the voltage on the Mobo Northbridge as crunchie pointed out.
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Old 07-04-2009, 06:06 PM   #7
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really? my 2 other voltages labeled "NB" and "NB 1.8" arent the northbridge chipset, but the hypertransport is? you should quote crunchie, cause i am having a problem finding where he said that. and if you still say that the hypertransport is the northbridge, i would like a diagram explaining that.
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Old 07-04-2009, 06:26 PM   #8
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o, i wasn't quoting crunchie on that end.

well incide the hypertransport voltage option there is the Northbridge Voltage is what I meant to say.
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Old 07-05-2009, 01:08 AM   #9
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Quote:
Originally Posted by sandeepb View Post
o, i wasn't quoting crunchie on that end.

well incide the hypertransport voltage option there is the Northbridge Voltage is what I meant to say.
that's right... your bios is most likely similar to the m3a32mvp setup. and i remember that... and mine is quite different... i believe the hypertransport is the pipeline(bus) between the chips... and i would like someone to confirm that i am thinking right.....
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Old 07-21-2009, 01:00 PM   #10
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I have a link for you that could prove useful.
http://www.techreaction.net/forums/showthread.php?t=367
It has some very useful information.
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Old 07-21-2009, 01:06 PM   #11
ELItheICEman
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Nice find Grubbworm. I saw that the other day and gave a few sections a read. It's pretty good stuff.
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Old 08-09-2009, 06:06 PM   #12
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Bios changeovers?

Hey while ago had comp that was ****ty ecs setup and when the board limited me like it is now in my current setup i was able to flash the bios wiht a biostar board equivlent bios and then get more setttings.....currently have the asus m3a yeah i should upgrade it but I want to find a way around the voltages not being tweakable for the nb and cpu....currently i cna only get it to 2.57ghz quad on my phenom 9750 asus m3a 4gb ddr2-800 1.24v sicne cannot change the cpu and nb....if neone know of a solution or a bios compatible with this board would be great help!
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