This thread is intended to be a simple tutorial for undervolting your Pentium M (Dothan) laptop. Undervolting the CPU reduces power consumption, thus allowing your laptop to run cooler and increasing battery life. I was able to adjust the minimum voltage of my Pentium M 760 (Dell Latitude D810) from 0.988V to 0.700V and the maximum voltage from 1.308V to 1.068V. Your mileage may vary!

1.) Download RightMark CPU Clock Utility (RMClock) from http://cpu.rightmark.org/ and Prime95 from http://www.mersenne.org/freesoft.htm
2.) Unzip the programs to the directories of your choice (I use /program files/rmclock/ and /program files/prime95/).
3.) Launche Prime95.exe, download and begin calculations, minimize the window (you should see a red icon in your system tray), then launch RMClock.exe.
4.) Click on the "General" tab and note your default voltages (mine are "Startup" and "Minimal" at 0.988V and "Maximal" at 1.308V).
5.) Click on the "Management" tab.
6.) Select the "Use P-State Transitions (PST)" box. Intel 855 and 915 chipset users may need to select "Run HLT command when the system is idle" (I did). Do not select or modify any other options.
7.) Make sure "Minimal FID" is at the lowest number (6.0x in my case) and "Maximal FID" is at the highest number (15.0x in my case).
8.) Change "Profile" to "Maximal" and click the apply button.
9.) Now click on the "General" tab and ensure that "Actual Clock" is your maximum processor operating speed (1995.16 Mhz in my case). Return to the "Management" tab.
10.) Decrease the "Maximal VID" (1.308V in my case) by one stepping and click the apply button.
11.) Ensure that Prime95 is still running without any errors. An error will look something like this: "FATAL ERROR: Rounding was 0.5, expected less than 0.4" or "Hardware failure detected, consult stress.txt."
12.) If you do not encounter any errors after a few minutes, return to RMClock and decrease the "Maximal VID" by another stepping.
13.) Continue decreasing the "Maximal VID" and checking Prime95 until you encounter an error. Make sure to press the apply button with each change.
14.) Once you encounter an error, raise the "Maximal VID" by one stepping.
15.) Then allow Prime95 to run for a few hours. If you receive an error, increase the "Maximal VID" by another stepping and run Prime95 for a few hours until you do not encounter any errors.
16.) If Prime95 runs for a few hours without encountering any errors, you have determined the lowest possible CPU voltage at maximum processor speed (1.068V in my case). Write this number down!
17.) Now change "Profile" to "Minimal." Repeat steps 9-15, except for "Minimal VID" instead of "Maximal VID."
18.) If Prime95 runs for a few hours without encountering any errors, you have determined the lowest possible CPU voltage at minimum processor speed (0.700V in my case). Write this number down!
19.) Change "Profile" to "Automatic Management" and select your recorded "Minimal VID" and "Maximal VID" values (0.700V minimal and 1.068V maximal in my case). Press the apply button.
20.) Select the "Advanced" tab and select "Apply these settings at program startup" under the "Misc Settings" area. Do not change any of the other settings. Click the apply button.
21.) Right click the RMClock system tray icon and select "Run Automatically at Startup" and "Start Minimized to Tray." You also may want to unselect "Force Minimal Profile on Batteries."

I will post my system improvements (battery life, CPU temperature, fan speed, etc) soon. People have reported amazing results, such as their CPU fans no longer activating at 0.700V, significant battery life improvement, and a noticable decrease in CPU and laptop temperature. Please let me know if this works for you and the results you are able to acheive. Good luck!

EDIT: Here is my data thus far (all under 100% CPU load for 5 minutes):

Minimal Speed:
Maximum CPU temperature @ 0.700V - 100 F
Maximum CPU Fan Speed @ 0.700V - 2399 RPM (variable on/off)
Maximum CPU temperature @ 0.988V - 107 F
Maximum CPU Fan Speed @ 0.988V - 2410 RPM (always on)

Maximal Speed:
Maximum CPU temperature @ 1.068V - 114 F
Maximum CPU Fan Speed @ 1.068V - 2422 RPM (always on)
Maximum CPU temperature @ 1.308V - 132 F
Maximum CPU Fan Speed @ 1.308V - 2944 RPM (always on)

great post.. i as playaing around with this tonight before you posted it thinking.. man.. i need some more scientific method to this aside from click and hope.

never thought to run prime 95.. good look@!

ah i think i see.. i can set it to max on the top and no management on the bottom.. and tell it to use min settings always on battery.. that means i get it as cool and quiet as possible but full speed plugged in.. and the mad battery saving goodness unplugged.

default low on mine was .7 already.. won't go any lower.

default high was 1.34 and it is down to 1.04 now.. pretty nice saving.. i can already hear the fan ging off a LOT less.

unfortunately allowingg it to throttle makes trillian act like a HO.

That's awesome! That's exactly what I was looking for. If you can't overclock the beast, undervolt it for better cooler temps, less noise, more battery life.

If you get a chance, run a couple battery drain tests (one with the factory default voltages and one with the new power saving voltages). Maybe loop Prime 95 for a couple hours?

Very nice needledik, thanks! Now I wonder what might be the drawbacks of undervolting... If they chose a specific volting, maybe it's not a good idea to tweak it. Really, I don't know, just asking.

Nice! I'll add that to the sticky as a link!!!

@MagicRobin: the value is set so that even the worse chips at severe conditions can function properly. Whit time production process improves and chips are over-all better, but by than it's too late to change the specifications and even if it weren't still every chip will have a different threshold, while only a small sample of every batch is throughrally tested.

^^^^

What he said.. its the same basic theory of over clocking, that being that the chips are produced in mass, tested for a certain freq, and shipped out... never mind that some of them can do quite a bit more, all the manufacturer cares about is that it can do what they are selling it to do.

wow great job Needledik

btw, my fan is staying off SOOOO much now.. it's running cooler. I had the thought to do this but your methodology made it much easier.. thanks.

Thats cool. (literally) Sorry. Anyway, I'm really looking forward to see how much more battery life you can get by undervolting. Thanks again!

I'm running some battery tests now. I will post my results later today.

I tried doing this and it froze at step 8. I'll try again now. I have a Dell Inspiron 6000d, specs are in my sig.

Sorry, to ask a stupid question.
By doing this will we void the warranty of the notebook?

No, for two reasons.

1) Undervolting the processor shouldn't damage it.

2) You're doing this in software; they can't tell if you've done anything.

Thanks needledik . My idle temps for my 1.6ghz is 30c. Max VID 0.988V Min VID : 0.812V. SYSTEM Dell 9300. Thanks. Goin to apply Artic Silver 5.