technology and zen of life

“A heisenbug (named after the Heisenberg Uncertainty Principle) is a computer bug that disappears or alters its characteristics when an attempt is made to study it.”

Bypassing the DELL unrecognized adapter issue

Dell is notoriously infamous for selling adapters that tend to go bad after few years of heavy usage. In the last 3 years of my laptop use, I’ve already had to change my adapter thrice due to an unrecognized adapter bios warning. You can read about why this issue occurs here .

I don’t really mind this message but dell has gone further to annoy their consumers by forcing a cpu throttle to the lowest scaling frequencies. Also, they will not allow you to charge your battery if this message pops up, for no reason but to force you into buying a new adapter. Since this is expensive business and all three of my dead and dying adapters work perfectly fine as far as the voltages required for operation are concerned, I was desperately searching for a software bypass to somehow allow frequency scaling on my CPU and work on reasonable speeds. However googling didn’t help much at which point I started reading up on BIOS and ACPI, the ones responsible for power management. Finally, I stumbled upon this beautiful solution to bypass this limit dell forces upon me.

On probing ACPI on the linux kernel I came across /proc/acpi/processor/CPUx/bios_limit which is the limit the bios is asking the kernel to respect. Hence, all one needs to bypass it is to ask the kernel to ignore bios_limit using a kernel parameter via grub namely processor.ignore_ppc=1. So just add this line to grub.conf [ or to GRUB_CMDLINE_LINUX in /etc/grub.d/grub if you’re using grub2] and you’re set.

Alternately, you can use rmclock[gui] on windows to achieve the same. However don’t forget to set the processor type to mobile if you’re using a laptop to get the right voltage values for various p-states. I hope this helps folks who’ve been annoyed by the way dell handles its adapters like me.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

56 Responses

  1. Henry Hudson says:

    Mike Dell knows what he’s doing. It’s not about making money selling batteries and chargers, it’s about lawsuits from fires leaving laptops unattended. BTW the youngest self made billionaire of his time, selling chargers and batteries is chump change for him.

  2. Former Dell field tech turned shop owner says:

    Wow, All these work arounds has anyone given a thought to why they have done this? it’s
    not to sell ac adapters. Can anyone say “FIRE”

  3. Jeff Tillwick says:

    “You raised my hope and dashed them quite expertly sir, bravo!”
    – Tiny Tim

    I was hoping this would also solve the dead battery problem.

  4. Rubber Meal says:

    Dude can u explain exactly how to do this ?

  5. joshua says:

    can someone explain this in a dumber version please

  6. Sigfried says:

    So, how do you achieve this same effect in Windows using RMClock?

  7. John Ackers says:

    The reason that Dell do this is to limit the current consumption on the power supply and so the laptop does not to cause the power supply to fry. Similar kind of things happens now with USB chargers for tablets.

  8. problem with using rmclock on windows, its malware

  9. Rob says:

    An alternative solution is to disable c-states and throttling in the bios.

    I disable this when I need to use my wife’s Dell charger, since mine is a 240 W and hers is 60 W. Works fine though.

  10. mozai says:

    processor.ignore_ppc=1 !!! Genius.

  11. dumbCAT says:

    My N5110 was anemic thru all last year, but I was so sure it might be some bloatware programs, fat updates, laggy windows or whatever you would like, so I disabled services startups.. etc. was doing different nonsenses. we would do when PC is laggng 🙂
    But yesterday batteries has stopped to charge. And laptop was so slow like an old android phone 🙂 Well CPU-Z showed my laptop DELL N5110 runs exactly 800 Mhz, intel boost technology does not works at all.

    Yes ThrottleStop helped instantly and returned me 2,9 Ghz.. wooha! But not so with batteries charging. So there should be better way return it back to life.
    Voltages amperages of original DELL adapter semed to be OK and DC jack was healthy. And I had chance test different DELL charger without luck.

    So problem was inside laptops DC part. So I disassembled apart laptop completely until was able take out DC module part completely. Sorry guys no photos but there was dirty white connector, please see this photo and there were not exactly dust, but something like oily dust. I believe there was some water or coffee incident I do not remember 🙂 Dust has colected and attached to connector pins and shorted them a bit somehow, so using strong magnifier and clean medical alcohol I carefully removed all dirt mess and cleaned contacts inside also.

    Please see picture, I marked problemic zone in red. After cleaning procedure – NO MORE AC adapter warnings in BIOS, laptop runs perfectly, batteries charges 🙂

    Please take care and think before disassembling your laptop and do it only if you trust your skills.
    Use only alchocol or suitable liquid for contacts cleaning!
    There is also nice video to see before disassembling to make life easier
    It helped me. It might help you guys. But if some dirt will be founded, magnifier is a must for proper cleaning!
    And tahnk you pointing to ThrottleStop. It`s nice piece of software 🙂
    Good luck!

  12. Exactly my problem says:

    You, sir, are a genius! Thanks much.

      • :) says:

        “After cracking the case of the DELL AC power adapter, brings about a mystery electronic component. It’s a transistor shaped component with 3 pins. The middle pin is connected to the AC Adapter Identification wire, the other pin to V- of the power plug. The 3rd wire is not connected. Pretty strange for a transistor, where all 3 pins are usually all connected.”

        “The casing of the transistor shaped mystery component has markings; “DALLAS – 2501 – 0613D2 – +571AA”. Not the typical markings on a transistor. Weird!!”

        “AC power Adapter – Dead communication

        After a few searches in the MAXIM component database, the transistor shaped device is a UniqueWare™ Add-Only Memory, known under type DS2501, DS2502, DS2505 or DS2506. The difference is the size of the memory. The DS2501 seems to be 512 byte memory. The memory is accessed using a 1 wire communication protocol known as “1-wire”.

        So the DS2501 in the DELL AC Power Adapter contains the identification info of the power adapter. The DELL laptop reads the identification info during startup of when it’s connected while started. Power for the memory device comes from the laptop which is the same AC Adapter Identification wire, indicated as a “parasite power circuit”.

        Pretty nifty solution – however, it proved to be a vulnerable one, with many victims. When communication with the UniqueWare™ Add-Only Memory fails, the laptop shuts battery charging down.
        No battery charging” !!!!!!!! 😀 😀 😀 😀 !!!!!!!

  13. VG says:

    if problem is like this:

    5 minute fix:

    the pins (4 nos) in jack lose with time (due to wear and tear of in bed usage)
    take pin, clear them and try picking them out so that they can again touch the adapter part!

    hope it helps,
    Trust me, I’m an engineer!

  14. Trytohelp says:

    Fix is only to prevent the throttling. Only a new power adapter will recharge the battery. My crappy Anker only last a few months before I started getting the Unrecognized error. I had a Kensington Universal Adapter that lasted several years, yet I never saw this error. My original Dell adapter only lasted about a year.

    Anyway with the error, the cpu’s speed was reduced in my case by 42%. The workaround in Windows as mentioned is to use a program called ThrottleStop.


    Before making adjustments within ThrottleStop, find out what cpu is in your Dell laptop and figure out what are the normal speed(s) and features of that chip.

    Read the 1st post from the above link. According to the author, Dell will either reduce Clock Modulation (CMod) or Chipset Clock Mod (Chip). Download, install, and run ThrottleStop. From the readings, whatever is not 100% as listed on the table is what you need to check before hitting Save. In my case, the CMod reading was 75%. So, I checked Clock Modulation to stop the throttling.

    Also make sure the Set Multiplier Number matches your cpu. The default listed was not the proper multiplier for my cpu.

    After the above steps, your cpu should now run at the maximum speed. That is great except laptop cpu’s run at multiple speeds to keep things cool and extend battery life. So, you probably want to check Power Saver or SLFM if the chip supports that.

    Post 2 from the link will explain how to use the Windows Task Scheduler to start ThrottleStop automatically when booting. Alternatively, you could also put a shortcut in the Startup folder in Windows if you prefer. If you are going to have ThrottleStop boot everytime, you might want to go to Options and check Start Miminized, Minimized on Close, and uncheck Task Bar. These options will make Throttlestop less intrusive so you do not have to do anything everytime you computer starts.

    • Trytohelp says:

      Don’t forget to click “Turn On” in ThrottleStop after making your check/uncheck choices and then Saving them.

      A good program to monitor your actual cpu speed is an application called CPU-Z. Download, install, run, and then minimize this program. That way, you can see what speed your cpu is running at while experimenting with ThrottleStop.

      In ThrottleStop, the goal is to match the power-saving and maximum speed your Dell laptop would get with a recognized adapter. In my case, the cpu is supposed to run at 800mhz at idle and 1400mhz as the top speed.

      You might have to experiment to get the right settings. No need to be afraid of checking or unchecking the wrong items in ThrottleStop. The worse that can happen is you set the laptop for the wrong idle and maximum speeds. You could always change it.

    • Everton Holtz says:

      Thanks, my inspiron 3442 now is running perfect. Hours finding a solution in internet lol. very good work of you. sorry bad english. Thanks from Brazil.

  15. Bojan says:

    So this is a fix for performance issue.
    Is there any fix or workaround to charge battery??

  16. Ryland says:

    This is what i need in my life, only problem is i have no idea how to edit kernels or whatever it is you are talking about. Im not computer illiterate by any means but could anyone give me a simple guide to do this on windows 8?

  17. A says:

    After a lot of web search and numerous forum threads, it was the comments here that finally put everything together and helped me solve the throttling problem on my laptop (Dell XPS M1330, T7250, with an ebay generic power adaptor).

    Not quite sure yet if this is the right solution but its better than having a 2.0GHz CPU be permenately throttled down to 1.2GHz.

    Thanks for your help.

    • A says:

      Forgot to mention that I am running Windows 8.1 and used ThrottleStop since good old trusty RMclock that have been using for ages did not seem to work for this problem. That is unless i am missing some option settings.

  18. Manuel says:

    I have an XPS15 with the i7-2630QM and was not able to get anything to work using RMclock. However, I was able to override throttling by unchecking “BD PROCHOT” in ThrottleStop. This allowed me to get full performance on AC power.

    • John says:

      I had the same problem and ThrottleStop fixed it. I had to use other options, in addition to unchecking BD PROCHOT I checked Clock Modulation, Chipset Clock Mod and Set Multiplier. Thanks to Amit and Manuel.

    • Scott says:

      I will kiss you on your curried little mouth! Thank you! By the way use throttlestop for win7 or 8 64 bit! BD PROCHOt took care of it immediately!

    • A says:

      This fixed it for me, too! Dell throttle my laptop to 700MHz after not recognizing the charger, but unchecking that box caused it to bounce back to full! Thanks for the tip.

    • Rubber Meal says:

      THX SO MUCH OMG U SAVED MY LIFE DUDE OMG THANKS SO FUCKING MUCH OMG OMG THANK U THANK U THANK U THANK U OMG U FUCKING GENIUS. lol i already tried throttlestop a month ago it said my card is not compatiable or something but i said why the fuck dont i try again and it worked so its all because of u in the end thx bro

  19. Falko says:

    Thank you so much for figuring this out and sharing your solution. Exactly what I was looking for. Great!

  20. Pascal Maillard says:

    Thank you so much for this excellent piece of advice, Amit. Already four years old, but still very useful.

    I had experienced the CPU throttling problem with my DELL XPS M1330 laptop (Intel Core 2 Duo T7250 @2GHz, BIOS version A15). The problem happened as soon as the AC power adapter was plugged in. It is a third party adapter by the brand LAVOLTA. The CPUs would throttle to 800MHz and changing CPU frequency via software in Linux Mint 15 would not help, neither with the cpufreq suite, nor with the CPU Frequency Scaling Monitor in the Gnome panel. Note that my battery still charged normally.

    Setting the kernel parameter “processor.ignore_ppc=1” at startup solved the issue! Although the “ondemand” governor still sets the CPUs to 800MHz permanently, I can set the speed to 2GHz manually, for example via the “performance” governor. Interestingly, if CPU 0 uses the “performance” governor and CPU 1 the “ondemand” governor, then CPU 1 correctly scales frequencies, but not if both CPU are set to “ondemand”.

    Note that I am not sure whether the LAVOLTA adapter is to blame for the issue: My laptop fell on the floor a few months ago, right on the spot where the power socket sits. So it might be that the socket itself is damaged. Unfortunately, I don’t have a working DELL adapter to check this.

  21. João Santos says:

    How do I fix this problem on Windows 7? I’ve downloaded RMclock but I couldn’t figure out how to do it. There is no option in this software saying anything about ignoring the bios_limit.

    Can someone please help me?

  22. Rob McColley says:

    This fix is written for coders. Could you write a version for dummies?

    I assume starts by going to Dash Home > Terminal

    Then what?

  23. How do I use rmclock to ignore the bios limit in windows? I am unfamiliar with terms like FID and VID, and I have no idea what to set them to! Also is it possible to force the battery to charge in windows? rmclock doesn’t seem to be able to do it.

  24. marcus says:

    You all sound mega tech savvy so this might be a stupid answer but i fixed mine by blowing down the end of the cable…..

  25. richard says:

    In Device manager uninstall microsoft AC Adaptor – unplug AC jack and then plug back.

    • thanks a lot Richard
      it was the simplest and easiest way to bypass that no charging and slow CPU issue.
      how did you get to this solution.?
      and thank u so very much again..i was managing with this piece of junk for over a month now

    • João Santos says:

      Unfortunately I didn’t have the same luck as nextdoor22oct.

      I uninstalled Microsoft AC Adaptor, followed by unplugging and plugging back the jack, but all it does is not showing the message “connected, but not charging” and the PC continue to run very slow.

      I did also disable an option on the Bios that allows Dell to “control” my CPU performance (I forgot the name) and it helped a little, but the performance is still far below the average.

      Is there any other solution to bypass this FORCED low performance, besides buying a new adapter? This problem is already getting to my nerves 🙁

      I’ll never buy a Dell product again.

    • Daniel Lewan says:

      Nice. Now he writes: plugged, not charging :>

    • Sam says:

      Thanks Richard.

  26. Jeremy says:

    Followed your suggestion, and the suggestion below for setting CPU to performance, and it worked great. Thanks for figuring this out I’ve been living with a slow computer for over a year!

  27. Is there anyway do it with Windows, please I need this to be fixed, if so please give me some clear instructions.

  28. riprop says:

    whenever using my universal car adapter (third party) for my Dell M4300 laptop I run on Dell unrecognized adapter issue (there is exact warning during laptop startup about it), so CPUs work all the time at 800MHz, which is annoying.

    I’m using Lubuntu / Ubuntu 11.10, 64bit.

    I tried solution with grub (as suggested here), adding GRUB_CMDLINE_LINUX=”processor.ignore_ppc=1? to /etc/default/grub, then update-grub but it didn’t solve the problem.

    Then I try with cpufreq-set:

    sudo apt-get install -y cpufrequtils

    modprobe cpufreq_ondemand
    modprobe cpufreq_userspace

    cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
    conservative ondemand userspace powersave performance

    cpufreq-set -c 0 -g performance
    cpufreq-set -c 1 -g performance

    and this worked, CPU’a was at 2.40GHz speed. A little issue was it was now fixed at maximum frequency all the time.
    You can monitor this by command:


    or in the loop:

    while :; do cat /proc/cpuinfo | egrep ‘GHz|MHz’; sleep 1; done

    This is my cpufreq-info (for one CPU only):

    cpufrequtils 007: cpufreq-info (C) Dominik Brodowski 2004-2009
    Report errors and bugs to, please.
    analyzing CPU 0:
    driver: acpi-cpufreq
    CPUs which run at the same hardware frequency: 0 1
    CPUs which need to have their frequency coordinated by software: 0
    maximum transition latency: 10.0 us.
    hardware limits: 800 MHz – 2.40 GHz
    available frequency steps: 2.40 GHz, 2.40 GHz, 2.00 GHz, 1.60 GHz, 1.20 GHz, 800 MHz
    available cpufreq governors: conservative, ondemand, userspace, powersave, performance
    current policy: frequency should be within 1.20 GHz and 2.40 GHz.
    The governor “performance” may decide which speed to use
    within this range.
    current CPU frequency is 2.40 GHz (asserted by call to hardware).
    cpufreq stats: 2.40 GHz:4.02%, 2.40 GHz:0.30%, 2.00 GHz:0.23%, 1.60 GHz:0.12%, 1.20 GHz:20.06%, 800 MHz:75.27% (2228)
    analyzing CPU 1:

    If I set it to ondemand governor:

    cpufreq-set -c 0 -g ondemand
    cpufreq-set -c 1 -g ondemand

    it sticks to 800MNz no matter CPU load !

    So I try different governors with or without CPU frequency limits, hoping it will not stick to minimum again, and only working solution for me was this:

    cpufreq-set -c 0 -g conservative
    cpufreq-set -c 1 -g conservative

    I hope this will help you to resolve your issue 😉

    Good lack !

  29. bub says:

    I beg you guys for some tips on how to do it with RMclock for Windows, I don’t manage and I’m scared to do something wrong as I have deadlines for work… There are sooooo many people having this problem and working in windows (I know, I don’t have a choide), please be our hero!


  30. Gaurav says:

    Thanks for the information. I tried RMclock on my Dell Latitude D610/Win XP with the power adapter problem. I couldn’t figure out how to increase the clock frequency back to the 1.73 GHz of the Pentium M processor installed. Do I play with the Target FID multiplier, with the Target VID multiplier or some other parameter? It is far too detailed and custom for my skill level.

    Thanks for any pointers.

  31. Warren says:

    Thanks for the tip regarding RMclock – it solved the throttling issue on windows quite nicely. On a similar note, would you happen to have any insight regarding the charging issue and a possible fix on a windows 7 machine?

    All the best,


  32. I have had ubuntu for some time on a Dell Studio 1735 laptop with the latest bios. I have used ubuntu natty (11.04) 64-bit for two weeks and subscribe to daily updates. Last Friday, I upgraded my cpu to an Intel core 2 duo T7500 from an Intel mobile celeron dual core T1500. The T7500 has a 2.2GHz maximum cpu clock and a four times larger level 2 cache than the T1500 which has a maximum 1.86GHz cpu clock. Both cpus, T1500 & T7500, are rated 35W TDP (thermal design power).

    The old T1500 always ran at 1861MHz according to the Ubuntu System Profiler and Benchmark utility. Sadly, the T7500 ran at 1200MHz upon installation regardless of what applications were running. The power supply for my Dell Studio is a 65W unit. Upon first boot with the T7500 cpu, the bios reported I should be using the Dell 95W power supply.

    I examined /sys/devices/system/cpu/cpu0/cpufreq/bios_limit which reported 1200000 (1200MHz) as the cpu frequency limit imposed by the Dell bios. No changes to the Dell bios settings made any difference to this limit. After doing some research, I followed your suggestion which fixed that issue – I added the line:


    to /etc/default/grub (see Remember to update grub if you do this!

    The /sys/devices/system/cpu/cpu0/cpufreq/bios_limit now reports 2201000 (2201MHz) as the cpu frequency limit. However, the actual cpu frequency rate remained stubbornly at 1.2GHz regardless of load. cpufreq-info reported:

    current policy: frequency should be within 1.20 GHz and 2.20 GHz.
    The governor “ondemand” may decide which speed to use
    within this range.
    current CPU frequency is 1.20 GHz.

    I had some success editing /etc/inid.d/local, inserting the lines:

    sudo cpufreq-set -c 0 -g conservative -d 1.6GHz
    sudo cpufreq-set -c 1 -g conservative -d 1.6GHz

    This script is executed at boot. In the above case, cpufreq-set, imposes a minimum frequency, -d 1.6GHz, on each cpu core, -c 0 & -c 1, and hands control to the governor “conservative” via -g conservative. This worked great for a brief period, only for the governor to change back to “ondemand” automagically and a complete end to any frequency scaling.

    Further research led me to edit the shell script /etc/init.d/ondemand which seems to get run regularly, imposing the seemingly broken “ondemand” governor instead of the perfectly functional “conservative” governor. I replaced the word “ondemand” with “conservative”:

    for CPUFREQ in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
    [ -f $CPUFREQ ] || continue
    echo -n conservative > $CPUFREQ

    My laptop now responds wonderfully well to load and I have no power supply issues or over heating.

    Best regards to all,

    Dermot McDonnell
    Castlebar, Mayo, Ireland.

  33. aaron Burrrell says:

    Worked Great. I have been trying to find this solution for months.

    Don’t forget to run “update-grub” for it to take affect.

  34. Alex says:

    Awesome, I’m gonna try this in the morning. Two quick questions.

    1) this is only a fix for the speed issues right? My battery will still be unable to charge? I’m assuming this is correct, if so, is there any way to bypass THAT issue?

    2) if I am running windows, but booting Linux(including grub) all off of an external hd and I still have the original MBR on the laptops hd. Will I be able to install grub without installing Linux on my harddrive? Even dual-booting is something I want to avoid on my laptop for a few reasons. Or will booting from the hd to grub, and then long-horning back to vista still load the right settings in order to bypass the speed limitations?

    Thank you much, this is valuable information


    • zer0701 says:

      In my case, the problem is on the laptop, not the charger, and there was no way I’d change my motherboard. After a lot of searching, I found a kind of fix. I can’t remember where I first read about this, but try the following:

      “SHANK that plug in. FORCEFULLY. Like, get your muscles ready, plug with full force and keep that force for about 5 seconds. After 2 or 3 attempts it should start charging.”

      This did work like a charm for me, but as time went by it started being less and less effective. Until I decided to try something that always helped with my headphones:

      Straighten the plug. Use silver tape or something so that the malleable part of the plug’s plastic cover is straightened out. Seems to have helped.

      Also, if your problem is on the laptop, not the charger, try opening your computer up and misting some lube (i.e. WD40) to the connector. Seems to help a bit.

      • zer0701 says:


        Charger is 100% dead. Upon dissection of the adapter’s corpse, it seems the metal plug is connected to the wiring via a plastic connector that’s so strong you can smash it between your thumbs. So I guess what I’d say is, following my method above will give you about a month (maybe more, maybe less… guess there’s a luck factor) of extra battery charging and no CPU nerf, but you’ll be hammering the final nail on your adapter’s coffin. 49min of battery remaining, then no computer until I buy another adapter. Guess Dell won in the end.

      • Sarii Wind says:

        You have literally just saved me infinite hours and money w/ the “jam it in” solution. The laptop is finally charging. Thanks so much!


The views expressed on this blog are personal. We do not claim to be a representative voice of the views of any organisation whatsoever. We are not responsible for the content present on the blogs to which we have linked.Views expressed are solely that of the author and does not reflect a collective opinion of contributors.
%d bloggers like this: