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)
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Sorry. Anyway, I'm really looking forward to see how much more battery life you can get by undervolting. Thanks again! 
I'll try again now. I have a Dell Inspiron 6000d, specs are in my sig.
