AMD64 Undervolting Guide

Everyone who is having heat management issues or suffering from short battery life with their AMD64 lappy, this guide is for you . First off, I do not claim this as original work. I took Laptop Logic's Advanced Battery Optimization Guide and updated it using my own personal experience, added the updated version of RightMark CPU Clock utility and a few extra tips. Please remember this is an "Advanced" guide, so if you plan to attempt this, you do so at your own risk. I will not be held responsible for any harm/damages for carelessness. Just like their site says

So, without further adue, here goes

There are 6 steps total in this guide.

1) First off you need these two apps:

RightMark CPU Clock utility
Prime95
Install both of them. It would be a good idea to reboot your machine before tweaking. Close all open application (even anti-virus).


2) Turn off power-saving mode.

Go to Start > Control Panel > Power options > Power Schemes > Home/Office Desk
Hit apply, then Ok.



3) Setup Prime95.

Start up Prime95, go to Options > Torture Test > select "In-Place large FFTs" > hit Ok.
Your CPU usage will go to 100%, that's normal. On your system tray you will see Prime95's red icon. This means it is working and error free. If at any time, the icon goes yellow, this means Prime95 has stopped working, most likely there is an error.
Leave it running.



4) Setup RightMark CPU Clock Utility.

Start up RMClock. Make note of your multiplier(fid) and voltage(vid) settings. For current, startup, minimal and maximal modes.

Note:
In the Main Program Settings part, select: "Run Automatically at startup", unselect "Restore CPU Defaults on Exit". The rest is up to you, this is how I have mine setup.


5) Finding the lowest voltage at maximum multiplier.

Select the Management tab. Select the "Use P-State Transitions" checkbox. Here is where the tweaking begins.

Select "Maximal" in AC Profile. You will only be tweaking the Maximal FID/VID (right side), don't pay attention to minimal (left side) for now.


Note: FID = Multiplier, VID = Voltage. The numbers show here are for my laptop, yours may vary. (And of course, you still have Prime95 running right?)

If you have never tweaked this before, both numbers should be at the highest setting possible. OK, what you will do now is lower the Maximal VID by the least possible increment. IE from 1.550v to 1.525v, since in my machine the least possible change is .025. Hit apply and wait 10 seconds (just count to 10), and repat the process.

This is where you really need to pay attention. AS SOON AS PRIME95 FAILS, YOU NEED TO INCREASE THE VOLTAGE(VID) SETTING BY 1. This is your lowest voltage setting for your maximum multiplier. It is advised that you increase your voltage by 1 extra setting, just in case, gives your machine a little room to breathe.

If your computer frezzes/crashes/reboots/whatever, just remember the last voltage setting, and increase it by 1.

Note: You can keep track of your current FID/VID settings in the Monitoring tab.


6) Finding your lowest voltage for your lowest multiplier.

Note: This is really just for those looking for the MAX battery life out of your machine while on the go. The way I have this setup, I sacrifice alot of core speed in exchange for battery life. You can of course, customize this to your own liking and/or needs.

Here you will only be tweaking Minimal FID/VID (left side). Set your min VID to its highest number. Move your min FID to its lowest setting.

Here you repeat the same process as in step 5. Lower your VID untill Prime95 fails. Increase it by 1 as soon as possible, increase it by an additional 1 setting, just for safety.


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That's it guys and gals!

Note: I have my AC Profile and Battery profile to minimal most of the time. I only change the AC profile to maximal when the gaming or doing any other heavy tasks. While using the maximal settings, you will NOT loose any clock speed. You can verify it yourself, I know it's important to some people ( like me ). At minimal, as I've stated before, you will sacrifice it. With the benefit of extended battery life of course.

The reason why I even know anything about how to do this is because my ac adapter kept overheating. The laptop overheated as well a couple of times. This being a new machine.. I found it anoying to say the least...

Using Asus probe, I've seen a major temperature range change with these tweaks. While gamig (HL2, CS:S, GW, UT2K4) I used to see temperatures of 70-75 celsius, now I see 55-60 celsius. Idling or light usage 55-60 celsius, now 40-45 celsius

And another amazing fact. I am able to use my Z80K with the fan OFF Silence is sweet

We'll I don't exactly know how to get precise measurements on battery life, but here are some using Window's estimated time left for the battery for my machine.

Normal (before tweaks): 1h 30min

Tweaked
Maximal: light usage 1h 50min, 100% cpu usage 50min
Minimal: light usage 2h 50min, 100% cpu usage 2h 5min

This is for my Z80K 3700+. Maximal is tweaked to FID: 12x, VID: 1.350v. Minimal is FID:4x, VID: .800v.

vinch, in theory, it should be the same for the P4.. Don't know though, only have this to work with so..

joybugoy, as far as I can tell no. Clock speed is FSB x Multiplier(FID), so voltage should not affect the end performance. If you only go up to step 5, you won't loose any core speed. If you also do step 6, you will have the option to clock it down for max battery life. I use the minimal settings for pretty much everything other than gaming. Even when I'm not on battery power.

Was it ever a mistery..?

And don't know, haven't read any guides don the P-M. Perhaps you could enlighten us.

I've seen it, just haven't read it. Just way too long, and don't have a P-M so... yea.

I originally got laptop logic's link from these forums.
http://notebookforums.com/showthread.php?t=61505