I have an ASUS k8n-e motherboard with an A64 3000+ processor. I have the CPU undervolted to 1.1V through the bios and everything is stable. (Lucky me I think)

When I enable cool'n'quiet, vcore is 1.1 volts when the processor is automatically underclocked, but when it runs at the full 2.0GHz vcore jumps right up to 1.5V, the normal voltage for the processor. Am I doing something wrong, or is it impossible to run cool'n'quiet AND undervolt at the same time? I know I could just turn cool'n'quiet off since my temps only go up to 36C with CPU burn-in and my CNPS7000 at 800RPM, but it would be nice if I could have the best of both worlds.

In theory there is nothing stopping you from using Cool 'n' Quiet together with undervolting. It won't work with the standard Cool 'n' Quiet tool however. For Cool 'n' Quiet to work, the bios supplies the OS a table with the valid multiplier / voltage settings, and the OS uses these values to switch between the different settings. But undervolting in the bios doesn't alter that table, it'll only change the currently used voltage (in theory, the bios of course could change that table, but I don't think there is any board/bios out there which allows that). So using Cool 'n' Quiet will ignore the bios voltage setting completely. Thus you need a Cool 'n' Quiet tool which ignores the bios-supplied table (or at least allows you to change it). There are certainly tools around that'll allow you to change multiplier/voltage on the fly, though I don't know if they also can do it automatically.

(me, I'm just using a hacked cool 'n' quiet linux kernel driver. I've just subtracted 0.2V from every table entry, so it switches now between 1Ghz/0.9V, 1.8Ghz/1.2V, 2.0Ghz/1.3V. Works great...)

mczak
btw that cpu you got is great. Really running at 1.1V, the board does not overvolt or something by default? I've seen some 130nm Newcastles A64 3000+ make it down to 1.2V, but 1.1V sounds really good.

CrystalCPUID is the program you want. Basically it replaces Cool'n'Quiet with a user-configurable table of voltages and multipliers. You can also change the response rate of the changes, and whether you want to go directly from low->high or high->low. A really incredible app.

What's the advantage of the A64 mobile? Does it tend to run stable at a lower voltage?

By the way, what PSU are you using?

The Asus board must be one of the best undervolters. I've heard the DFI nForce3 board undervolts, but I doubt it does by that much!

EDIT: nevermind, I just reread the A64 article.

mczak, thanks for such a clear answer, and thanks for all the replies

To answer a few questions...

It really is running at 1.1V, well, according to ASUS probe its actually 1.12V, but who knows how accurate the reading is anyway.

The only problem with this is that the bios warns me whenever I boot the computer, it gives a CPU overvoltage error (Would it be a big deal for them to have a separate warning for low voltage and high voltage?) , so I have to press F1 every time I boot. I haven't figured out a way to bypass the warning. An annoyance, but I'm not rebooting very often.

I have the same problem if I enable q-fan 2 on the cpu fan. Its impossible to set the start temp low enough for the fan to start at ambient, so I get a CPU fan error when I boot the computer if qfan is enabled. I can't imagine how you could use qfan on the CPU fan without getting an error actually. If someone knows a way around this wow I would thank you multiple times. In my ideal world, I would use my z7000 alcu with the fanmate turned all the way down, and qfan set to 4V when the CPU is cool without getting a boot error message. This operates the CPU fan at about 600 RPM. Silent as far as I'm concerned, but really goes a long way in keeping the CPU cooler than if passive. I don't really want to turn off my CPU fan ever, even though I idle under 35C with the fan off (in part because of the cool weather here in Berkeley).

I haven't had my computer crash a single time since setting it to 1.1V. So in that respect, I've gotta say I recommend the ASUS k8n-e for those wishing to undervolt an A64. Its all in a Sonata with the stock 380W TP.

I'm going to try out CrystalCPUID right now, but have a feeling I would use it on a permanent basis. It seems like a better more stable idea to just disable c'n'q since I'm running so cool anyway than to use some dude's beta software and have to run an extra program at startup. I will give it a whirl though and will report back.

Ok, so I just tried CrystalCPUID, and I have mixed feelings about it.
For one, my regular cool'n'quiet driver kept overriding it. I'm sure there's a way to fix that, but I didn't know how off hand. So it would take the new settings for a while, then revert without notice.

I did learn that the CPU at 4X and 5X multiplier is stable down to 0.8V, as low as the program would let me set it. The bios only lets me go to 0.85V.

So for now I plan to stay running full speed all the time with C'n'Q disabled at 1.1V. With my fan at 677RPM I can't really justify slowing down the processor to make it cooler. I think my next step is going to be to take off my rear case fan and just have a 2 fan setup with PS and CPU fan as my 120mm case fan is by far the loudest component in my system. This will require covering all of the openings except for the front intake so I still get adequate flow over my HDs.

Temperatures are so nice and cool now that in some ways I'm not looking forward to getting a new vid card, but its a must because I just got a second monitor, and my current card doesn't support two monitors. But thats another cooling challenge for another day.

What is the method you use for checking if it's stable?

Yes, CrystalCPUID does assume the function of Cool'n'Quiet. Therefore you must disable Cool'n'Quiet to make it work properly (by setting power management to anything but "minimal").

I'd certainly hesitate to call it "beta" software, it is in version 4.0+. It does consume 1.1MB of RAM, and in the last 48 hours of running it has required 1 second of CPU time.

If you create a file called cpuid.reg and set the contents to read as follows:

Or just grab the file here. Then it will start silently and automatically minimised to the system tray.

These are my settings and they work incredibly well. I think it's pretty self explanitory, but let me know if you have any questions.

Look in the mainboard manual at page 4-32 and 4-33.
In the BIOS Boot menu, set Wait for 'F1' If Error to [Disabled].

I don't have your mobo, but on all my other Asus mobo's that works.

I have a Asus K8N which is the lower spec version of your board, but the BIOS appears to be similar.

Tibors suggestion will allow the motherboard to boot without pressing F1 but it will cause your board to beep violently. Your best bet is it to tell the sensors to ignore the readings. To do this, go into hardware monitoring in your BIOS and highlight the VCore reading. Press enter and select 'ignore'. This will stop the motherboard deciding that the reading is a danger and stop both the F1 error and annoying beeps. If you really need to know the Vcore, then use Asus probe or speedfan in windows.
As for Qfan just do the same as for the Vcore, disable the monitor and the problem disappears. I have found that Qfan wont stop my fan once it starts, which is why I have decided to use speedfan instead.

Hope this helps...

I have noticed this as well. Kind of annoying, but it does slow the fan down enough to be inaudible.

Wow, I would have sworn that I'd tried setting those things to ignore, and that it didn't work, but I guess I was mistaken. I feel like such a n000b. And yes, there are supposed to be three 0s there.

Thanks for the help again.

Questions answered-
I check if its stable by:
Running prime95 for a few hours
CPU Burn-in with error checking for a few hours
And seeing if general use causes errors such as 3D gaming, and regular email, web stuff, etc.

So far I haven't had any problems during any of these tests with the settings I have described.

I can happily say my computer is booting without getting upset with me now, and is idling around 32C with the CPU fan off, but set to kick on if I go above 35C.

WOW that is one good chip!! That can't be using more than 30w at full load, truly brilliant. Unfortunately for me i got a clawhammer, which doesn't like going under 1.3v @ 1800Mhz. When it's locked down to 0.975v @ 800Mhz the temperature doesn't rise above 40c with the fan off. Speedfan turns the fan on at about 42c.

Btw, glad i could help