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100% CPU Usage After Unplugging AC Power

by tamas413 / December 9, 2009 7:26 AM PST

I've had Win7 for a few months now (thanks to MSDN Academic Alliance) but I've just recently started having this problem. I'm running Win7 Professional on my HP HDX16 laptop. My laptop basically runs flawless when plugged into AC power. When I unplug it, however, CPU usage skyrockets to 95%-100%. I managed to look at the task manager one time at noticed that it isn't necessarily one process that is crippling my computer; It's more like 4 or 5 programs that run around 20 CPU and the rest of the processor is used by various other programs. The process hogging programs vary sometimes, but it usually includes audiodg (audio device graph), mcshield (Mcafee), and a few other svchost (usually Win Defender, Win Firewall and AudioEndpointBuilder). I have the IDT HD audio card for those wondering (and all of the latest drivers from HP). Does anyone have any ideas as to how I can fix this?

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Might be proper.
by R. Proffitt Forum moderator / December 9, 2009 8:06 AM PST

Read up about how the OS may shutdown a core, and scale back the clock rate. This means it could push the CPU load to 100% but at a lower clock rate. Sorry if I stop short of a dissertation but this could be proper behavior.

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Only when unplugging...
by tamas413 / December 9, 2009 9:54 AM PST
In reply to: Might be proper.

The thing that confuses me is that it only does it when the computer is running and I unplug it. When I wake it from sleep when unplugged, however, it operates at a fairly low processor usage percentage rate (~20%).
If it is proper operation for it to lower the clock speed and/or disable a core when it is unplugged, is there anyway to disable it?
I would much rather have a functional laptop that dies quickly than one that conserves power by crippling itself.

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Windows 7 laptops only shipped recently.
by R. Proffitt Forum moderator / December 9, 2009 10:53 AM PST

You can tweak the power profiles to get around all this. But the machine's story is too light for me to make any other suggestions.

Tell more and explore the power profiles.

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I'm sorry...
by tamas413 / December 9, 2009 11:18 AM PST

i should have explored the power setting earlier. I didn't find anything indicating that it slowed the processors down when on battery power. Here are some of the settings.

I have figured out, however, that the slowdown takes place usually when I'm watching any kind of video (Hulu, NBC and even video calls on Skype). I'm not exactly sure how switching from AC power to battery power when watching a video makes a difference though.

Audio - IDT High Definition CODEC
Video - NVidia GeForce 9600M GT
Processor - Intel Core 2 Duo P8400 (2.26 GHz)
OS - Windows 7 Professional 64-bit

Thanks for your help.

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Even in that picture.
by R. Proffitt Forum moderator / December 9, 2009 10:35 PM PST
In reply to: I'm sorry...

I spotted something different from battery to plugged in. Try setting it all the same. is dated but shows that even the older dual cores could do this shutdown.

Why battery or plugged in matters has to do with how processes could be lumped onto one core rather than spread across the cores (plugged in) so what you are seeing sounds proper. Try setting the power profile for battery to be one like plugged in.

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If it's still on warranty return it
by Dango517 / December 11, 2009 1:29 AM PST

Sounds like it could be a bad motherboard.

Check the CVS file for a corrupt file, more then likely the the services programs. This is a long file start at the bottom and read up through it. Window Vista in Compaq PCs had a repair function to repair the services sector in BIOS, F8. You might need a recovery disc to repair it if is a corrupt file. Are you using registry repair software, by the way?

Get a CPU meter and check if all the Cores are running. There are several gadgets for this for Windows 7, Sidebar.

This thread untracked.

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Exact same problem here
by brunno.santos / December 14, 2009 11:21 PM PST

Hello everybody...

I'm from Brazil.. I'm experiecing the exact same problem you are!!!

The CPU usage only gets to 100% instantly when I unplug the AC Power... Have no idea of what's going on... i've already tried everything...

This s**t happens when running any Windows 7 version... professional, ultimate, home premium... pick one... I've tested and confirmed this.

My notebook is a HP DV4-1225 BR... BIOS and drivers updated... but I've also tested without any drivers, just the clean installation, and nothing.

Not only it gets 100 cpu usage on normal mode but as an administrator too.

It doesn't happen when running another OS.. such as ChromeOS, Windows Vista, Windows XP, Mac OSx86...

Is there anybody else on earth that is experiecing this problem?

Tried HP Support Forum too, but not a single answer... =/

(Yeah, it also works for me when the notebook goes to sleep mode on ac power and then, when plugged out, it wakes up on batteries normally - no full cpu usage in this case.)

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This is one for the maker.
by R. Proffitt Forum moderator / December 14, 2009 11:33 PM PST

Microsoft is not the right place to ask for a fix. They don't make the machine and just like the early days of XP, Vista you saw things like this. If I were to bet it is the BIOS at play here and there is only one place to go for that.

If you don't know which company, just ask.

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HP HDX 16 1060ES - Windows 7 Home Premium 64 bit - CPU 100%
by justbrook / January 2, 2010 9:39 AM PST

Hello guys,

I have similar problems with my laptop. I reinstalled (not upgraded) Windows 7.

The config is:
HP HDX 16 1060ES - Windows 7 Home Premium 64 bit

Sometimes - even without reason - the CPU usage jumps to 100% and every process runs soooo sloooow like I had a computer with a 100Mhz processor. The mouse is moving properly, but the native Windows buttons interact very slowly. The machine becomes totally useless because of the expanded reaction time. If I listen to music this time it plays very very very slow as well. Sometimes Google Chrome's Flash plugin ( crashes too but I think that's just an Adobe/Google thing.

And after a while (10 minutes) the issue ends and everything is fine - for a while. And it starts again without any reasons.

I think it is not Google Chrome, Flash Player or AC thing. Isn't it some Windows process that goes crazy? I tried to search for some suspicious process in the Task Manager, but seen nothing special.

The memory usage goes up to maximum 40%.

If someone knows the solution...

Thanks in advance,

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Yeah, looks like it's a process issue
by brunno.santos / January 4, 2010 2:50 AM PST

After checking Administrative Tools >> Event Log and Task Manager, I've found something curious... Windows Management Instrument (WMI) service crashes right after I unplug the ac power... but... I still don't know how to fix it.

Ps.: Ocasionally the problem happens even when ac power is plugged, as previously said above...

Any ideas?

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Use Task Manager
by TaraS_WinTeam / January 5, 2010 4:33 AM PST
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Task Manager
by justbrook / January 5, 2010 4:55 AM PST
In reply to: Use Task Manager

Hello Tara,

I tried it many times:
audiodg.exe --> up to 50%
System Idle Process --> up to 50%
taskmanager --> up to 50%!!!

The problem is the machine becomes so slow that opening the task manager itself is a real hassle. Whatever you do this time happens very very very slowly.

What I think is something can be wrong with the audio driver. When I use winamp or gmail video chat after a while the sound starts to rag and delay. After that the computer becomes very slow and in a short time the CPU usage jumps to 100%. After then there is no stopping the mess, restart is the only way.


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Same problem in HP HDX 18t
by Callmetimm / January 8, 2010 9:23 AM PST
In reply to: Task Manager

I'm so glad I found this thread. I'm having this same problem on a quad core HP HDX18t laptop that I upgraded to Windows 7 (64 bit). It runs flawlessly when plugged into AC power, but when running on battery power the CPU usage skyrockets to 95%-100%.

The task manager doesn't show one process that is out of control, but rather a handful of programs that are running higher than normal for a total of 100%. These processes vary, but are frequently audiodg, SpySweeper (Webroot AntiVirus), and a few other svchost processes.

I initially had this problem after upgrading my computer using using an off-the-shelf version of Windows 7 Ultimate . But I've twice tried wiping my machine with the HP system restore disks, then upgraded using the "official" HP build of Windows 7 Home Premium. I've updated the machine with all the latest drivers and BIOS.

I'm really at a loss here. If it doesn't get fixed with a system restore & the latest drivers, I'm not sure how I can fix it. Anyone else find something out that could help?

It looks like several of us are experiencing the problem. We all have HP computers. Sounds like it could be a problem with the BIOS or some driver issue.

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Did you contact HP?
by R. Proffitt Forum moderator / January 8, 2010 11:08 AM PST

Many don't.

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Contact HP?
by Callmetimm / January 8, 2010 11:29 AM PST
In reply to: Did you contact HP?

I've talked to three different technicians. In fact, I'm on the line with one now. I'll write back if I find a fix.

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Here's the deal.
by R. Proffitt Forum moderator / January 8, 2010 11:40 AM PST
In reply to: Contact HP?

I only cured it a few times. If I count Vista. We had to update the BIOS, the drivers and then be sure we were unplugging any non-HP gear during the tests. If non-HP drivers are wacky then the fun is trying to pin down who's going to fix it.

On a personal note, after watching all this I waited till Windows 7 shipped installed and ready to use rather than suffer like others.

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Still working on it
by Callmetimm / January 10, 2010 11:32 AM PST
In reply to: Here's the deal.

I spent about 1.5 hours talking to the HP tech support guy - he suggested I wipe my system again with my system disk and revert back to Vista just to see if the problem still happened. I did a clean install of Windows 7 instead and my machine seems to be working well. Although I've only installed about 75% of the HP drivers and a handful of apps.

I am getting warnings from HP Advisor to download HP Battery Check, but they don't seem to have a Windows 7 version available. I'm wondering if that caused problems in my upgrade from Vista?

Just for the record, I could reproduce the problem in the past by starting my TV tuner software and unplugging my computer - the CPU usage would go straight to 100%. Playing media in Windows Media Center and Hulu also caused problems. Although playing music with Windows Media Player seemed OK.

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100% CPU usage after unplugging the AC adapter
by jayx1988 / March 26, 2010 2:24 AM PDT
In reply to: Did you contact HP?

i have this problem as well in windows 7 64bit and i have tried this method:

1. use your computer in AC adapter mode
2. change the power option in control panel or the battery icon on the taskbar
3. then choose edit plan setting/change plan setting
4 choose the advance settings and you will find a window pop up
5. check the "processor power management", and under the minimum proceesor state, i change it to 100% instead of 5% for both "high performance mode " and "hp recommended mode". (i haven tried the power saving mode as i seldom choose that.)

6. then put in the battery and unplugg the ac adapter to check whether it works or not.

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wrong info..sorry
by jayx1988 / March 26, 2010 2:44 AM PDT

sorry, i gave the wrong solution

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by TaraS_WinTeam / January 12, 2010 3:01 AM PST
In reply to: Task Manager
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CPU showing 100% usage
by SAMURAI164 / April 8, 2010 1:15 AM PDT

Hi Mr.Brazillian,

.....from INDIA...

i too ve the same problem of 100% cpu usage in windows 7 ultimate and sysyem getting hang on often. i dont know why it is happening and when does it happen . just it happens.
dont know to find the soln for the same.
if you get any soln pls notify me .

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Did you the fix noted in this discussion?
by R. Proffitt Forum moderator / April 8, 2010 2:45 AM PDT
In reply to: CPU showing 100% usage
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Same problem with my HP HDX +cpu to 100% on battery
by sashank_1234 / January 11, 2010 11:34 PM PST

I have exactly the same problem.
I have even done and clean install and also a upgrade from vista.

I can tell you even after a clean install .just open the task manager and cpu goes to 100% when on battery

works flawlessly on vista 64 bit on battery

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Seems to be a real problem.
by R. Proffitt Forum moderator / January 12, 2010 12:51 AM PST
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Clean install
by Callmetimm / January 12, 2010 1:35 AM PST

I've reinstalled most of my apps after a clean install and my machine still seems to be working. Was yours failing immediately after the clean install or did you install any HP drivers afterward?

The HP tech told me to downgrade to Vista 64 to see if that worked. If it had, he would have declared the hardware OK and the problem the fault of Windows 7. In other words... not HP's fault.

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Same problem with my HP HDX +cpu to 100% on battery
by sashank_1234 / January 12, 2010 3:13 AM PST
In reply to: Clean install

i did both

1)clean install - then installed only nvidia driver - no other drivers - Same problem

2)Upgrade from vista -> same problem.

just did a clean install and fired up the task manger to see cpu at 100%..DAMN again

I researched this a bit and used process explorer and found some hardware interrupts.
any idea??

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To reproduce... for those interested
by tamas413 / January 12, 2010 3:33 PM PST

OP here. In my case, the best way that I can reproduce the problem by being on AC power and being on a Skype video call and unplugging the computer. The picture instantly freezes and the audio is garbled (imagine a robot drowning).
Of course, this isn't the only trigger, it's only a (rather) reliable way to reproduce our problem.

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So it's not stock?
by R. Proffitt Forum moderator / January 12, 2010 8:41 PM PST

Skype is not a stock load and with that the makers may write you off. I was under the impression you could do this with the factory load. Install ANYTHING and they walk out on you.

There is another high CPU item called WERFAULT but I see that no one may be able to nail this one since there are programs being installed that are not from MSFT or the machine's maker.

That is, you won't get HP, MSFT to chip in to help because you had a problem after using SKYPE. For that you need to see about SKYPE support.

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I think it does not matter
by justbrook / January 12, 2010 9:42 PM PST
In reply to: So it's not stock?

If you use Skype, GMail video chat, you watch a DVD on Media Player, listening to music with Winamp or browsing a website with Google Chrome.

Does not matter what you software you use, your computer dies after a while.

It must be a Microsoft / HP problem.


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It must be.
by R. Proffitt Forum moderator / January 12, 2010 10:11 PM PST

And this one will go down with a lot of hurt feelings I fear as many don't want to accept the responsibility.

Frankly? It's time to return the beast and go with some other model.

I know I've worked this issue before but each and everytime we cured it but then again we had it in the shop and they followed the directions of the factory load, BIOS and all that.

WERFAULT is however a new item I'll bring up and let me share it appears to be a real problem for some. I hope to run into that soon so I can see if my theory holds up on why that fails.

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