Solved: 100% CPU usage on Acer Aspire 1640Z

Do you have an Acer laptop? Is the CPU going full bore for no reason? Is your battery getting a bit old?

Then do I have a solution for you.

Fun problem at work this week, as above. The SYSTEM process – not the System Idle process, as you’d expect – was eating as much CPU time as it could, causing it to heat up and run its fans like crazy. Oh, and the laptop’s keyboard and touchpad were practically useless – it was ignoring 9 in every 10 keystrokes, and you’d get maybe 2-3 responses a second out of the touchpad.

I had to plug a USB keyboard and mouse into it; curiously they worked flawlessly. I guess it was too busy to listen to its PS/2 inputs.

I googled “system process using cpu“, and landed on an essay by Mark Russinovich (the Sysinternals guy) on how he used Process Explorer to hunt down whatever was using his CPU like crazy. His problem turned out to be bad network card drivers; in my case…


…it was something called Deferred Procedure Calls. A further google for that turns up a surprising number of Acer laptop users. This thread explains it all. There’s a hardware bug somewhere in the way certain Acers – at least the 1640Z, and some 3000 and 5000 series models – talk to old batteries. Possibly they’re getting hung up on it reading too close to zero, I don’t know.

The fix is simple. All you have to do is pull the battery out.


CPU usage will instantly decrease, and everything will return to normal until the next time you reboot with the battery slotted in.

If this is your problem, you have three simple options. First, you can chuck the battery out, leaving the laptop to rock from side to side on a flat surface because some of the feet are on the battery; two, you buy a new battery, gambling it’s the battery’s fault and not the laptop’s; and three, go buy yourself a shiny new laptop that isn’t crap.

Edit: I’m getting a lot of hits from people with recent Acer laptops, saying they have full CPU usage. This exact problem is to do with old batteries; if you’ve got a Core2 Acer or something similarly recent, it’s not the same problem and I can’t specifically help you. I suggest checking Task Manager (ctrl+alt+del, pick it from the list) and looking in the Processes tab – find what’s using your CPU, google the name of it and kill it. Aside from that I can’t really help.

41 Responses to “Solved: 100% CPU usage on Acer Aspire 1640Z”

  1. felixt says:

    Wow! You just confirmed the problem that I’m having with my Acer 4060. It was behaving like described for few months now, and only last night I figured out by having the battery unplugged the CPU usage returns to normal..

    Needless to say, will be staying away from Acer laptops from now on..

  2. Garrick says:

    My father had an Aspire 3662, and he had this problem… neither he, nor the computer shop he bought it from Googled for this (nor me, till I got home. 😛 ). I did just what you said and it fixed it fine… pity he ended up buying another Acer from them… now I have a toy laptop…

    Thanks for the blog.

  3. lokesh says:

    I am glad to see the solution….

    But I have VISTA having the same problem,,,,,,,,,,,,,,,,,,,,,

    Can u give any solution to solve the same problem in vista

    i am very very thank ful , if u give the reply

    Windows vistan Home premium

    3 GB ram

    Intel Core 2 duo

    Thanks for reply

  4. tim says:

    If that’s a Core2 with 3GB RAM, it’s not going to be the same battery-age-related problem.

    Do what I did, get Process Explorer and see what’s chewing the CPU, and we’ll go from there.

  5. fulvio says:

    Have had nightmares for the last three days, CPU usage at 50% minimum, keyboard out of use (me too had to buy a USB one), I couldn’t figure out what the issue was with my Acer??!? tried everything from spyware to killing processes, rebooting in various modes, system restores etc etc… was about to do a complete reformatting when I noticed the battery was indicating 255% full, which is some how a strange figure… I have simply unplugged the power chord and let it die… it’s all back to normal now!!! then found your blog and it’s all clear now! thanks!

  6. Teuneuuns says:

    Aspire 1640z, system process at 100%, no keyboard, no pad, old battery…
    Same problem… same solution…
    It works fine now
    Thank you!!

  7. Stormlord says:

    OMG!!!! Thank you, thank you, thank you!!
    This has been driving me insane for a week!!! I’ve lost sleep over it.
    Such a simple solution ….

    Wish it had been easier to find. It was many a google search before I happened upon this page….

    Acer Aspire 5050 … no pad – no keyboard – system process 80% + all the time.


  8. techBlog » Blog Archive » Acer Laptop Woe says:

    […] Googled around using battery as one of the keywords led me to search results that confirmed the problem. This particular post is particularly useful: […]

  9. Brett Sabell says:

    Awesome, worked for me too! A friend of mine had an Acer Aspire 1640, and this solved the problem.

    Now, wish me luck trying to find a new battery for a 4-year old laptop! 🙂

    Thanks man!!!

  10. noturvendor says:

    I have the same problem with my acer laptop 5920… except I dont run it on a battery. There is no battery in it, its just plugged into the wall and yet the cpu usage skyrockets. Any more suggestions?

  11. tim says:

    Hi noturvendor,

    You could try what Felix did with his, which was to disable the ACPI battery device, see here on how to do that:

    If that doesn’t help, grab Process Explorer and see what’s chewing the CPU, same way I did.

  12. Randy Cutad says:

    I just bought an ASPIRE 3810T laptop (core2 solo processor, Vista) a month ago and I got the same problem described above. CPU usage is 100% even without opening any file? And it will no longer respond if I will open a file, it becomes very slow….This happens when my laptop heats up. I’m so frustrated with this laptop honestly. Pls help me on this! I’ll be very glad if you could…

  13. Djam95 says:

    tank you for this soluce
    it is exactly my problem

    very, very tank

    Djam95 – France

  14. darkan9el says:

    Cheers, this had me totally confused, but I got the Acer 3630 onto AC and pulled the battery… and wadda ya know system idle at 98% and no cursor jitters, will buy a new battery and let ya know what happens.

    All I need to do now is sort out the launch manager taking 92% cpu on startup. if I shut luanch manager down and restart it, its fine until I restart. Crazy eh!

  15. Surfer says:

    Thanks for that post…. That was my problem too… Acer Aspire 3005 WLMi. I had exactly the same symptoms, so I pulled out my battery. Voila, Windows working as good as new again. If I would just find that post sooner…..

    I spent the whole day with this! I knew the hardware was OK, because in linux everything was working w/o any problem, I scaned for viruses and malware, so that was out of the question too, so I started blaming drivers of course…. After reinstalling all the drivers, the problem was still there…. stupid battery handling!!

  16. Firdaus says:

    Thanks Tim,

    Your solution really helped me! But I only came across your blog after I’ve restored my notebook twice 🙁 Looks like the battery on my Aspire 1690z is dying. Time to get a new battery or if the battery is too expensive, I just might as well buy a new notebook.

  17. cheap computers says:

    Acer Aspire 3005 WLMi. I had exactly the same symptoms, so I pulled out my battery. Voila, Windows working as good as new again.

  18. Sam says:

    My 1680 laptop i REALLY bad for this, the battery is old but still lasts maybe 30-45mins.I get jitters in the cursor and the keyboard misses out keystrokes. Every so often when the laptop is at idle it spikes to 10-20% every 5 seconds or so. I have also tried EVERYTHING, process explorer, malware bytes scan and so on….

    Pretty sure its the Deferred Procedure Calls as well.
    HOWEVER another thing I have noticed with this laptop is that anything java causes 100% usage, e.g facebook chat ends up running the CPU at 100% and I ca hardly use it.

    I think this will be unrelated to the old battery problem, i’ll test tonight and let everyone know.
    Anyone got any clues to the high cpu usage on webpages like hotmail, facebook etc, anything with banner adds moving pics etc. Photobucket is very bad at times also. I end up having to close the browser

  19. Sam says:

    Ok it worked pretty well, still some issues with facebook and hotmail grinding it to a halt sometimes (java issue somewhere i believe) and internet explorer using GOBS of memery per page. Like 100-300mb sometimes, PERPAGE!!

    However the 20% spikes for deffered proceedure calls are gone, there are other tiny spikes in places but now i can watch HQ youtube movies pretty well. Overclocked the video and CPU so this helped even more.

    Anyone know if a 1690 motherboard fits into a 1680 laptop? (better chipset, better overclocking with pinmod)

  20. JuanGuillermo says:

    sorry my english, Thanks a lot, thats is my problem with aspire 5000, somebody had bought, another battery and solved the problem?, or is the main board of the laptop. sorry my english

  21. tim says:


    Try taking the battery out. If the problem goes away, you can buy a new battery to fix it.

  22. gutrix says:

    OMG, thx alot
    This resolve my issue.

  23. Francesco says:

    Thank you for sharing this tip, and for pointing to Felix tip about disabling battery device. This was very, very useful.

  24. Portatili Acer, vecchia batteria e utilizzo del processore « GiBiLog says:

    […] chiave” del problema (Acer, notebook, battery, cpu) è stato facile trovare la risposta. In questo articolo (in inglese) sono spiegati tutti i dettagli del problema nonchè le varie possibili soluzioni. In […]

  25. Caleb says:

    You sir are a scholar and a gentleman. You saved me from a potentially fruitless OS re-install. For that I thank you.

  26. Jibs says:

    Thanks!!! Did the trick. I thought this old Acer was ready for scrap heap.That will have to wait a little longer…. 😉

  27. Solo says:

    Oh!!! Dear, Thanks that is really GREAT help.

  28. george says:




    (ACER ASPIRE 1692WLMi)

  29. Booker Sophy says:

    Heya i am for the primary time here. I found this board and I in finding It truly helpful & it helped me out much. I am hoping to offer something again and help others such as you aided me.

  30. nzlpablo says:

    OMFG I love you.

    (worked for my old acer aspire 3000)

  31. PauloPablo says:

    Im pull out the battery but i still have a problem with this 100% CPU usage
    what else i have to do ? i mis something?

  32. bap hanh laptop says:

    bap hanh laptop…


  33. PhiSch says:

    Kiss my shiny metal a.. – I had that very laptop on my desk for weeks and had no idea what’s going on.
    After reading your post, I got the problem fixed in seconds, huh!!! Thank you very much for your detailed
    report on this issue, can’t believe that it is so easy…

  34. Ricardo says:

    Thnk you so much ! It solve my problem on Windows 7 in aspire 1640

  35. hosearama says:

    Have an Acer Aspire 5336 2524. Had this problem for over 2 years since. I removed the battery and it stopped. My battery was NEVER old, however. Will never by Acer again. They’re crap.

  36. Aleks says:

    FUCK man i was fuckminded about 2 months, and ur post helped me out !!!! THANKS MANN !!!!!!!!!!!!!! PEACE !!!

  37. devilivedevil says:

    acer aspire 3000
    hogged to death by system process,
    removed battery, all good now

  38. speezy says:

    Well …here we are in 2016…and I got this Acer Aspire 5534 for my daughter back in 2009. She had always complained about it being slow. Had it sitting around a few years doing nothing and tried to convert it into a PLEX server and kept getting error messages that the CPU was not strong enough..which I knew was crazy becuase I have an old XP machine from 2006 that did just fine acting as a PLEX server

    So I was just about to through it away, and thought one last try. Freshly loaded W7 on it, then started noticing the fan would never go off. Took a look at CPU usage when nothing but the OS was running and CPU usage was at 55, and would jump to 70….just at idle. ” Well that’s not right!”

    Googled and didn’t find an answer, and was just about to throw the darn thing away, and for some reason I clicked on your post. “Really?” I said to myself. Took the battery out and rebooted..and BINGO..CPU back into normal territory. FYI, if you try and put the battery back in with it running on AC power, usage jumps right back up and even if you then subsequently remove the battery, the CPU stay peaked until reboot.

    Good stuff. Thanks for posting this all those years ago. Looks like I now have a back-up PLEX server when my old XP machine craps out.


  39. Biz says:

    same damn problem on a brand new acer switch 11…. let that be a warning for peeps considering this crap :@

  40. Amy says:

    OMG! Thank you! I was about to lose my mind but, turns out, battery is shit! I’m so glad to find that this was was the problem.

  41. zz2ipper says:

    Worked for my old Acer Aspire 1410 Timeline netbook. TYVM