CPU Undervolting: Athlon 64 3000+ at 1.1v

After hearing several success stories about undervolting, I decided to try it myself. I have an nForce4 Ultra board made by Chaintech using Award BIOS. Undervolting in BIOS is very easy.


1) Go to the Frequency/VoltageControl screen from the main BIOS menu
2) Enable Voltage Fine Tune, it is the 4th one from the bottom
3) Now you can change the CPU Voltage, it is the 3rd one from the bottom

The default voltage for A64 3000+ Winchester is 1.4v. I set mine to 1.3v, 1.2v, and then 1.1v. The PC runs great at these voltages. I haven’t tried beyond 1.1v. The original idle temperature was at 33C with Cool&Quiet enabled, now it idles at 26-28C at 1.1v. The room temperature is at 72F. The Zalman 7000 CPU fan is only spinning at 850 rpm. At this rpm, I guess even the AMD stock fan should be quiet. If you have a hot CPU, try undervolting.



Cooling NB47J with SpeedFan 4.25

As soon as I got my motherboard, I replaced the noisy chipset fan with a passive Zalman NB47J heat sink. Then I measured the NB47J’s temperature using a digital thermo probe. It is 63C at idle! That means the chipset core temperature is even higher! The heat sink is too hot to touch. I was worried about the longevity of the motherboard, so I mounted a Panaflo 80L (made in Japan) directly above NB47J using two steel wires. (Zalman FB123 was too short to reach that far.)




Here is a newer photo.

I originally plugged the 3pin connector to the chipset fan header on my motherboard. NB47J temp dropped from 63C to 33C-34C! A hefty 30C drop! The Panaflo was blowing at full speed. It is not loud but I can still hear it, so I wanted to lower the speed. Then I searched “VNF4 speedfan” on google and discovered the following webpage.

http://www.gadgetbuilder.com/Computer/SpeedFanInfo.html



I plugged the Panaflo 80L into the Fan3 Case Fan header.



In SpeedFan 4.25, I set Fan2 to “Software Controlled.”


Then I set the speed between 60%-70% and auto variated.


The I set the desired Temp2(System Temp) to 29 and warning temp temp at 38C. I was told that the Sys Temp sensor is some where around the chipset. When my Sys Temp is at 29C, the NB47J Temp I measured with a thermo probe is about 35C-36C.

Now the NB47J is at 35C-36C and I could no longer hear the fan, unless I put my ear one inch away from it.

I notice that the chipset fan doesn’t spin during boot. Here is how to solve that problem.


1) If you have Cool’n’Quiet enabled, both CPU fan port and Fan3 port will be in Auto mode by default. I like the combined effect of Cool’n’Quiet and undervolting, so I leave the Cool’n’Quiet enabled.


2) Go to the PC Health Status menu from the main BIOS menu, then go to Fan Speed Control.


3) Change Case Fan Control from Auto to Disabled.

When in Auto, the Panaflo is off when booting, it won’t be on until WinXP is up and SpeedFan starts running. In Disabled mode, the fan port will be on during boot and SpeedFan will lower the speed to 70% when the program is loaded.


Conclusion

1) Undervolting can lower CPU temp quite a bit.
2) You probably have onboard fan controllers you aren’t even aware of. You can use SpeedFan 4.25 to control the fan speeds on these ports.

With these two techniques, it is very possible to build a quiet PC even with the stock CPU fan and the stock chipset fan. You probably don’t need a separate fan controller either.

You can click the url below to download the SpeedFan.

http://www.almico.com/speedfan.php

The latest version 4.25 supports events, which can beep, execute a program, or popup a message to alert you in case the CPU overheats or a fan fails, etc.

I learned so much from this website, and I want to share a few useful techniques I know that are effective. My original post wasn't very clear on instructions. So this time, I added many photos and step-by-step instructions to my original post. I hope this will be helpful to many people.

Hyperq - your post is greatly appreciated by this non-techie who hadn't until now considered undervolting. I'm planning to upgrade to a similar chip and thanks to your very helpful step-by-step walk-through I may well follow suit!

hyperq,
thanks for the info!

thanks for this, i thought i would need to use a controller, but now i know i can just use speed fan to do it.

thanks