Undervolting Your Dell: A Guide To Less Heat & Longer Battery

Undervolting is the practice of reducing the supply voltage of a computer's CPU. There are many reasons to perform this sort of modification, but a common one is to reduce power consumption and thus heat generation in laptop computers. Lower heat generation provided by undervolting and underclocking is also helpful in making computers quieter and prolonging laptop life.

I am always looking for ways to improve my battery life or give my laptop a cool break anytime I can to help it out. I started reading about undervolting a few days ago and decided, hey I am going to try to this to see if it works or not. So I went, did a little research and downloaded a few programs and got to it. Here is what I did and my results.

RMClock------| Download |

Prime95--------| Download |

RightMark CPU Clock Utility (RMClock) is a small GUI application designed for real-time CPU frequency, throttling, load level monitoring, and on-the-fly adjustment of the CPU performance level on supported CPU models via the processor's power management model-specific registers (MSRs). In automatic management mode it continuously monitors the CPU usage level and dynamically adjusts the CPU frequency, throttle and/or voltage level as needed, realizing the "Performance on Demand" concept.

Over the years, Prime95 has become extremely popular among PC enthusiasts and overclockers as a stability testing utility. It includes a "Torture Test" mode designed specifically for testing PC subsystems for errors in order to help ensure the correct operation of Prime95 on that system, which effectively stress-tests a PC.

1. Go download the two programs listed above.

2. Install RMClock. Prime95 does not need to be installed.

3. Start up the Rightmark CPU Clock Utility.



4. Open up the Profiles Tree and click Performance On Demand



5. Your VID settings are the stock voltages set by the processor’s manufacturer to ensure your processor gets enough power at each FID (clock multiplier for your cpu). The defaults that come on your CPU are actually more than what is needed to run your CPU and are only recommendations to keep your CPU running stable. By changing the VID settings for each FID and doing a stress test, we can effectively reduce the required voltage needed to stably run your CPU at each FID which will result in less heat production from your CPU and also increase overall battery length while unplugged.

6. So lets get down to the nitty gritty. At the Performance on Demand window, click Use P-state transitions (PST) under the AC power and Battery icons.

7. This can change for different users and your needs, but when I use my laptop unplugged I am doing nothing but surfing the internet or watching movies on the go. If I am playing games usually I am sitting down and am plugged in. I only need about 50% of my processors actual potential while unplugged so I only check Index 0 in the table below for battery. In the AC power table, I checked all Index 0 – 7 because I plan on using the full potential of my processor while plugged in. At the bottom of the window where it says Target CPU usage level (%) I set AC power at 85 (it will still utilize the whole processor not sure why it doesn’t go to 100) and battery at 50 and click the Apply button.



8. Now click on the Profiles tab. Change all four of the Current and Startup tabs for the AC power and Battery to Performance on demand.



9. In the table below are the VID settings (already set by CPU manufacturer) for each of the CPU’s multipliers (FID). The lowest VID available was already set for Index 0. According to what we have chosen so far, I have set my CPU to only run at Index 0 (FID 6.0x which is 50% of my CPU’s speed) while I am using my battery. Since I cannot go any lower I will leave it alone. (Just a note: I did run Prime95 for 15 minutes while using only Index 0 on the battery without any stability issues.) Uncheck all but Index 7 under the AC power for now. The VID listed for Index 7 is what is recommended to run your CPU stably. What we are going to do is bump it down in increments to reduce power consumption and run a stress test to ensure it is stable enough for us to use under max load. I would start by dropping it by no more than 2 lower than what is already set at.



10. Click the apply button to save the changes you have made and open Prime95.

11. When Prime95 comes up, choose the Blend option. (Disclaimer: If you are concerned with creating high temperatures for your CPU due to stress testing I recommend you do not go on further with this process and I will not be held accountable for any problems you could encounter.) Click OK to start stress testing your laptop and minimize Prime 95.



12. Click the Monitoring tab in RMClock and look at the graphs that are available. Your top graph (CPU core clock and throttle) should be all the way maxed out while the Prime95 stress test is running. Also you can monitor the temperature of your CPU on the bottom of the screen and your FID and VID are also displayed in a graph.



13. I let Prime95 run this test for 15 minutes to ensure no errors occurred and then stopped testing. Now go back to the Profiles tab and decrease your VID for Index 7 again and click apply. Repeat Prime95 stress test. Keep doing this until you actually encounter an error or your computer crashes. (Note: From my research online and what I experienced, your computer crashing will not mess anything up, just do a reboot and load windows normally and you will be fine.) Once your computer crashes you have found out the lowest VID you can go at the highest FID of your processor. As a rule of thumb go back into RMClock and set your VID for Index 7 two settings higher than what you crashed at. This is where I would run a long Prime95 test on that setting to ensure stability.

14. Now that you have found your lowest VID for your max FID (Index 7), you can also do the same for your lowest VID for your lowest FID (Index 0). As stated above, the lowest VID for mine was already set and I tested it prior, so I did not have to do testing for it. To do testing on it, you would check only Index 0 in the profiles tab and repeat steps 11-13. This can be done for all Indexes you wish to change, just do one at a time.

15. Once you find out what VID’s you need in your Profiles tab, make sure all Index 0-7 are checked on and click apply. Go to the Performance on demand tab and under AC power ensure all Index 0-7 are checked. Do the same for the Indexes you wish to use while on Battery under that. Click Apply.

16. Now the VID’s you tested and clicked to use will be used by your CPU when it reaches each multiplier (FID) level. The last thing to do is to go to the Settings tab in RMClock and check the Start minimized to system tray button. (DISCLAIMER: If you have saved unstable VID’s in your Profile and clicked to use them and your computer starts up and runs RMClock, it will try to use these unstable VID’s and cause your computer to crash. Ensure you test the VID’s you change to ensure system stability prior to having RMClock run at startup. IF you do for some reason save unstable VID’s and have a problem, boot your computer in Safe Mode and turn it off of your startup there.)

17. You have now reduced the amount of heat your CPU is outputting and hopefully extended the life expectancy of it by at least a small amount. Also you just increased your battery life while running on battery power and can get that extra time you always needed.

So how do you know I’m not blowing smoke up your…uhh…hindquarters? The results of my testing before and after I undervolted my computer:

Before: Prime95 (15 minutes) - 100% CPU @ 1.25V (stock settings)
170 degrees F Max
145-152 degrees F running
Room Temp = About 53 degrees F

After: Prime95 (15 minutes) - 100% CPU @ 1.10V
145 degrees F max
123-125 degrees F running
Room Temp = About 53 degrees F
^ STABLE ^

*I used CPUID’s Hardware Monitor (HWMonitor) to check Min/Max/Running temps and to monitor temps.

That’s a 25 degree drop just by doing the testing and setting this up…all for free. Results may vary depending on what type of CPU you have. For this test I was using an Intel Pentium Dual Core T2370 rated at 1.73 GHz (actual 1728.53MHz) configured with the specs listed in my signature below. I was actually starting to worry about lowering it to much as I had dropped my VID for Index 7 more than halfway down the list. Just make sure you run Prime95 for at least 15 minutes or so when testing your VID’s out to ensure you stay stable. I ended up leaving mine at a level I was comfortable with without pushing it to the max all the way down until I crashed.

Also do not get confused while doing this. Undervolting your processor does not decrease the performance of it. Underclocking it does. The Indexes you select to use in your Performance on demand for the AC power will utilize your entire CPU 100% (Indexes 0-7) with no underclocking, just undervolting (lowest possible power consumption at each output). If you selected just Index 0 under the Battery, it will underclock and undervoltage your CPU while on the battery, thus utilizing only the amount of processor power (in my case 50%) you select to use when on the battery. This is why there are Indexes for each option: AC power and Battery. The target CPU usage level can be adjusted in the Perfomance on demand tab if you wish to use more than 50% while on the battery. Also this is only changing how much power your processor uses, not anything else on your computer so you will not have power issues with anything else.

Hope you all can make use of this. All I ask for is some rep (and maybe sticky this if possible) if you found it useful and if you would like to post any results of your own testing please feel free to do so. Also if this was confusing at all and you wish to do it or are doing it and have a question just ask and I’ll respond asap.

(Only pic hosting website I have access to ATT is cardomain, sorry)

- Gater

 

Good job.
However,
http://forum.notebookreview.com/showthread.php?t=235824

 

*sighs* I think I should just keep my ideas to myself and stop posting on here. I'm sorry for posting things on here, I don't have the bandwidth right now to be searching the forums looking for things all the time. I will try to search next time before I do any testing, etc and write guides. Thanks for making me aware.

 

I was by no means discouraging you. I think you did a great job. Perhaps you could post a thread asking what guides are needed and work on those?

Here's a list of guides. Perhaps you could work on something else that isn't in there?
http://forum.notebookreview.com/showthread.php?t=125803

 

Thanks for that link, checking it out now. I just usually check the Inspiron forum as I and my wife have one. Plus I have crap for bandwidth while aboard this boat (a page on the forum here takes 2-3 mins to load). Guess I need to broaden my horizon lol.