Is undervolting still useful on a CnQ motherboard?

gavinm · Post by **gavinm** » Tue Jun 22, 2004 7:39 am

Well, the title says it all really...

I'm a bit confused as to whether having undervolting support on an A64 motherboard will ever be useful on a motherboard that already fully supports Cool'n'Quiet. Can anyone illuminate me?

Thanks,
Gav

gavinm · Post by **gavinm** » Tue Jun 22, 2004 12:09 pm

Anyone???

hydroxyhydride · Post by **hydroxyhydride** » Tue Jun 22, 2004 7:52 pm

Well, you can do what i did here and take advantage of CnQ to do your own custom underclocking/undervolting which can be far more agressive than CnQ default.

jojo4u · Post by **jojo4u** » Wed Jun 23, 2004 2:20 am

Cool'n'Quiet has no use when the CPU has to work really hard.

gavinm · Post by **gavinm** » Wed Jun 23, 2004 3:23 am

hydroxyhydride,

Do all motherboards allow you to configure CnQ to the same extent that your K8V deluxe does? There seem to be a number of posts on these forums from people asking whether a particular mobo, which they know supports CnQ, also supports undervolting. E.g.:

http://forums.silentpcreview.com/viewtopic.php?t=13554

NeilBlanchard wrote:Does the MSI Neo motherboard support Cool N' Quiet? (Does CPUID show the clock dropping when the system is idle?)

Does it support CPU undervolting? If so, you might be able to cool it a lot even at 100% load! And you could Fold for the SPCR team...

If what you say about your K8V deluxe holds true for all CnQ mobos then why are people asking this question? (Is it just ignorance, like me?)

Am I safe to buy any nForce3 250-based mobo safe in the knowledge that its CnQ support will allow me a free reign with regards to undervolting?

Sorry if I am labouring the point, but I just want to make sure that I don't end up making an expensive mistake when buying my mobo...

Gav.

gavinm · Post by **gavinm** » Wed Jun 23, 2004 3:32 am

jojo4u

Cool'n'Quiet has no use when the CPU has to work really hard.

From what hydroxyhydride says it sounds like it has: if CnQ allows you to specify voltage at the various CnQ levels then you can potentially undervolt your CPU even when it is running at 100%.

But this is the question I am trying to get to the bottom of...

Gav

jojo4u · Post by **jojo4u** » Wed Jun 23, 2004 5:38 am

gavinm wrote:Do all motherboards allow you to configure CnQ to the same extent that your K8V deluxe does? There seem to be a number of posts on these forums from people asking whether a particular mobo, which they know supports CnQ, also supports undervolting. E.g.:

Am I safe to buy any nForce3 250-based mobo safe in the knowledge that its CnQ support will allow me a free reign with regards to undervolting?

Ok, here a better explanaition how I understood it:

hydroxyhdydride has Cool'n'Quiet enabled in the BIOS, but has not configured Windows to use it. The enabling of Cool'n'Quiet in the BIOS unlocked better undervoltage options. He is now able to undervolt and underclock the CPU down to 1,4Ghz@1V with the help of ClockGen.
The CPU is fixed at this frequency, so this is not "Cool'n'Quiet".

All Cool'n'Quiet capable motherboards are able to undervolt. If the user is able to adjust the voltages, that's another story. The ClockGen utility page says, that you can adjust the Voltage-ID for every nForce3 board.

What remains unclear to me: If you have selected a lower default voltage, and you're using Cool'n'Quiet in you operating system, what voltages are choosen for the different P-States?
Seems to be the right time to buy an Athlon 64 and play a little bit around with it...

Jan Kivar · Post by **Jan Kivar** » Wed Jun 23, 2004 7:41 am

Here's how I see it:

All processors have a given nominal operating voltage, so do the A64s. Undervolting in BIOS means that we're running a processor spec'd to run 1.5V with only 1.4V. In addition to this, the Cool 'n' Quiet feature drops the frequency/voltage lower at near-idle situations. When the CPU is stressed, it speeds to the max. frequency @ 1.4V.

If this doesn't apply, then one would have to turn C'n'Q off when overvolting also?

Cheers,

Jan

gavinm · Post by **gavinm** » Wed Jun 23, 2004 8:12 am

Jan,

But if CnQ gives you the option to set voltage, frequency & multipler ratios for all modes (even the 100% CPU one) then you have the ability to overvolt as well as undervolt.

I'm just not sure whether it does, although some people seem to be suggesting that this is, indeed, the case...

Gav

Jan Kivar · Post by **Jan Kivar** » Wed Jun 23, 2004 8:40 am

gavinm wrote:But if CnQ gives you the option to set voltage, frequency & multipler ratios for all modes (even the 100% CPU one) then you have the ability to overvolt as well as undervolt.

I'm just not sure whether it does, although some people seem to be suggesting that this is, indeed, the case...

That was my justification for my previous paragraph.

I haven't played with A64s, therefore I'm more or less quessing here. I'd like it to work as I described, but as hydroxyhydride showed in his thread, using 3rd party software opens more options than any BIOS has.

Cheers,

Jan

gavinm · Post by **gavinm** » Wed Jun 23, 2004 9:17 am

Jan,

hydroxyhydride wrote:I am running Windows Server 2003 and the CnQ driver doesn't seem to work properly

I'd presumed this was why hydroxyhydride had been forced to use ClockGen, and, I must admit, I was more than a bit confused by hydroxyhydride's initial post in http://forums.silentpcreview.com/viewtopic.php?p=107043.

So, if I now understand correctly, I DO need to find a mobo that supports underclocking in addition to CnQ if I wish to have the CPU run undervolted when it is running at maximum CnQ P-State???

But if you can undervolt separately to CnQ, then what voltages would be used for the other CnQ P-States?

And if you use ClockGen, does it override CnQ completely so that the CPU always runs at the same speed with the settings you have set in ClockGen?

Gav

Jan Kivar · Post by **Jan Kivar** » Fri Jun 25, 2004 1:16 am

Gav, the answers to your questions are something I'd like to know as well. I hope that hydroxyhydride or SpyderCat would answer to them.

Cheers,

Jan

SpyderCat · Post by **SpyderCat** » Fri Jun 25, 2004 2:11 am

Jan Kivar wrote:Gav, the answers to your questions are something I'd like to know as well. I hope that hydroxyhydride or SpyderCat would answer to them.

Cheers,

Jan

I hear you

CnQ seems to use the same mechanisms as ClockGen does, so any changes made by ClockGen are changed around when you enable CnQ.

Depending on your CPU you can have different voltage/speed settings with CnQ.
For my CPU these are:
1.5 volts @ 2000 MHz or
1.4 volts @ 1800 MHz or
1.1 volts @ 1000 MHz.
Changes are triggered automaticly by CPU-utilisation.
Like: running a utilisation of more than 80% @ 1000 MHz makes the CPU switch to 1800 MHz, thereby dropping the CPU-utilisation.
Even when you've set the VCore @ 1.4 Volts in BIOS, once CnQ starts to mess with your machine it's up to the default 1.5 Volts again.

Now, I prefer undervolting using ClockGen as ClockGen is more "cutting edge", albeit not switching automaticly (yet).
With ClockGen I can run:
1.3 volts @ 2000 MHz or
0.85 volts @ 1000 MHz or
0.80 volts @ 800 MHz.

So, running @ 2000 MHz I can feed my CPU 0.1 volts less than CnQ does when running @ 1800 MHz.
Switching from one set of settings to another set is done by using shortcuts, and I have 1 shortcut in my startup-folder so that setting is applied when booting into Windows.

Is it more clear now?

EDIT:
ClockGen works just fine when I have CnQ disabled in BIOS, so pick a board supported by ClockGen.

hydroxyhydride · Post by **hydroxyhydride** » Sat Jun 26, 2004 1:47 am

Hello. Sorry for any confusion I may have caused.

My first experiment was undervolting in the BIOS of my K8V Deluxe. At stock CPU speed (10x200 = 2.00 Ghz) I was able to only get to 1.4Volts. So taking this for what it was worth, I abandoned further "classical" undervolting attempts and took a different approach.

I tried to force CnQ in the BIOS but my operating system was incompatible with the software aspect of it. Also, I was running Folding @ Home as a background service so I needed a little more control over the voltages under load.

Then I stumbled across ClockGen from one of the SPCR threads (I don't remember which one) and tried playing with it. ClockGen would crash the computer (hard lock, no blue screen of death) if I tried to change the multiplier of the CPU--this was with CnQ in the BIOS disabled.
Only after I enabled CnQ in my BIOS, was I able to start changing the CPU multiplier using ClockGen.

I can only guess as to how this process works with other motherboards but this is a summary of my experience with the process. Hope this clears everything up (although it seems that this thread has pretty much wrapped things up without me)

gavinm · Post by **gavinm** » Sat Jun 26, 2004 9:18 am

No need to apologise, hydroxyhydride... Your posts have been most helpful. You (and the others who have taken the time to post) have probably saved me many hours of experimentation and frustration!

Thanks again,
Gav.

Jan Kivar · Post by **Jan Kivar** » Sat Jun 26, 2004 11:04 pm

SpyderCat wrote:CnQ seems to use the same mechanisms as ClockGen does, so any changes made by ClockGen are changed around when you enable CnQ.

Is this "enable in BIOS" or "enable in Windows" (via the driver/Control Panel->Power Options)? Deducing from hydroxyhydride's posts, from Windows, right?

Cheers,

Jan

SpyderCat · Post by **SpyderCat** » Sun Jun 27, 2004 1:44 am

Jan Kivar wrote:
SpyderCat wrote:CnQ seems to use the same mechanisms as ClockGen does, so any changes made by ClockGen are changed around when you enable CnQ.
Is this "enable in BIOS" or "enable in Windows" (via the driver/Control Panel->Power Options)? Deducing from hydroxyhydride's posts, from Windows, right?

Cheers,

Jan

Read "enable" as "activate", and to activate CnQ you need to:
* enable it in Bios
* load AMD's CPU driver
* set power-management to "minimum power" in Windows

When all this is done, CnQ can change the same "dials" as ClockGen can.
It's like having 2 pilots flying the same plane. When they don't work together it gets messy.
Also I found CnQ overrules any setting you used for VCore in BIOS.

CnQ lowers your average power-consumption when the CPU works mostly below 100% utilisation.
With ClockGen you can lower your power-consumption at a choosen CPU-speed, and you can choose your CPU-speed.

Jan Kivar · Post by **Jan Kivar** » Wed Jun 30, 2004 6:25 am

Thanks for the clarification, SpyderCat. Seems like ClockGen is the way to do it then.

Cheers,

Jan

brianstretch · Post by **brianstretch** » Fri Jul 02, 2004 1:51 pm

My HP zv5000z Athlon 64 3200+ notebook (DTR chip, not even the Mobile version) has a very robust two-fan cooling system and appears to undervolt as well as the desktop boards. I used ClockGen to tweak the voltage and multiplier and Hot CPU Tester 4 Lite to verify. 2GHz @ 1.3V worked, as did 1.8GHz @ 1.2V (which is the same as the Low Voltage Athlon 64 2800+, only that chip has half the L2 cache as my 3200+ DTR). Heat output at 1.2V is very mild. I haven't tried other settings yet. I suspect 1.8GHz @ 1.2V is the sweet spot. That should provide lots of gaming battery life, what with the 12 cell battery

. Normally the notebook drops down to 1.6GHz @ 1.3V on battery.

Does anyone know how to tweak voltages under 64-bit Linux? I put an Athlon 64 3200+ Mobile chip in my K8V Deluxe desktop running 64-bit Fedora Core 2 exclusively (64-bit UT2004 rocks with the new nVidia drivers released the other day). Changing the CPU speed is easy, normally I let powernowd handle that automatically, but I don't know how to undervolt.