CPU usage suddenly jumps to 100% for no apparent reason

Question

I have a Latitude D600 with Windows XP. For the past two days, my CPU has been going nuts. I will be doing normal daily activities with only a few programs open (IE, AIM, and iTunes usually), when suddenly everything will slow down to half speed/lag or whatever. Opening task manager, under 'processes' it will show CPU usage at 100%, and the main programs will show that they are using much more CPU than usual (ie: iTunes usually is around 5 for me, but it shows up as high as 74). Even when I close all applications, it takes at least 5-10 minutes before it recuperates enough to start functioning normally again. I think it happens about once every hour [with activity] or so, but I have not paid close attention to the time span.   I have Symantec Antivirus and Webroot Spysweeper (as well as an internet program called 'Clean Access Agent' that my college's internet uses to allow safe logons), and I've swept, updated, done everything I can think of to find any worms or viruses that might be causing this, and I've come up empty-handed. I have not downloaded any new software recently. This has never happened before; it's just the past two days that my poor little laptop has been acting up. Any ideas? Thanks so much for taking the time to read this!

bacillus · Answer

have you tried turning off the indexing service to see if it makes any difference?

pileofmanga · Answer

No, I have not. I'm not too knowledgeable about most computer functions ^__^; however, I did manage to find the 'indexing service' on my computer, but I'm not sure how to turn it off, or if it's even on. I've never known about it before, haha. Could you explain it for me, please? Thanks so much for your response!

bacillus · Answer

if you found the indexing service under services then just double click the entry and choose disable fom the drop down list>apply. you can always enable it later if you wanted.

notladstyle · Answer

Your CPU may be overheating - when this happens the clock speed is cut in half in order to aid in cooling it off.

Of course, cutting the CPU speed by half will make it much slower. Check your vents for dust and verify the fan is running.

aRenegade · Answer

I'm experiencing a similar problem right now with my Inspiron 6000 Win XP sp2.  My problem started about six or seven weeks ago.  I'd be working on the normal routine stuff, have a couple of applications open, then it would seem that all of a sudden whatever application that I was working with, would 'slow down' for about 10 to 20 seconds, then go back to normal.  At first I thought that I had encountered the dreaded 'bottleneck'.  So I go hunting trying to figure out what program was responsible for the system drain.  Well I couldn't find any memory hogs but still, I'd be working on something when everything would slow down.   And where I really noticed the 'slow downs' was when I would be checking out streaming content or the occational game play.  So I get 'What's Running' and discover that the frequency of my cpu which is normally 599, would occationally drop to 598.  I pinned down that when the cooling fan would kick in that was when the cpu frequency would drop, and then go back to 599 when it stopped.  I checked all the vents and everything is clean so I ruled that out as being the culprit (and confirmed that the fan was actually running).  I'm currently still on the hunt...

pileofmanga · Answer

I finally managed to get a compressed air can and I sprayed the heck out of my computer. I already knew that dust collects easily in computers, but EW. There was so much in my laptop. Now my battery keeps comfortably warm instead of worryingly hot, and my computer hasn't lagged once since! I will never neglect dusting my computer again. Thanks so much for the help! Have a great day ^__^

TallerMike · Answer

I seem to be having the same problem as you aRenegade. My D600 laptop slows down suddenly for a number of seconds. At some point, it began to not recover from the slow down on it's own. I looked at the processes and nothing was using up all of the CPU or memory. Oddly, putting the laptop in standby and bringing it back out would fix the problem. I ran through all of the diagnostics tests and nothing seemed to be wrong. I've since replace the hard drive with a larger one and reinstalled Windows. While in the process of updating the drivers (before any other software was added), it slowed down again. Makes me think it's a hardware issue. Anyone have an idea?

notladstyle · Answer

@TallerMike wrote:
I seem to be having the same problem as you aRenegade. My D600 laptop slows down suddenly for a number of seconds. At some point, it began to not recover from the slow down on it's own. I looked at the processes and nothing was using up all of the CPU or memory. Oddly, putting the laptop in standby and bringing it back out would fix the problem. I ran through all of the diagnostics tests and nothing seemed to be wrong. I've since replace the hard drive with a larger one and reinstalled Windows. While in the process of updating the drivers (before any other software was added), it slowed down again. Makes me think it's a hardware issue. Anyone have an idea?

It IS an hardware issue - its called overheating because the vents are clogged with dirt or the laptop is sitting on something that blocks the vents.

aRenegade · Answer

First of all I want to say thanks for the response. I agree that dust build up can have an affect on a processor however, I ruled out my problem as being thermal related. Dell boards come with thermal sensors and on average my PC runs 96°F - 101°F. Under heavy loads in a “warm” workroom I’ve hit 107°F tops, but when that happens the fan gets kicked into overdrive and the temp drops right back down to its average range. Those numbers are well within Intel’s operating specifications. Besides, if the problem was thermal related a CPU spike would repeatedly track with the temperature, and mine doesn’t.

My suspicions are that the answer to this problem lies somewhere in this equation; Workload (running services) x Resources (memory) x Applied Voltages (fan) x IRQ sharing (interrupt request) and temperature play a minor role in it. Even though the device manager doesn’t register any conflicts doesn’t necessarily mean that’s true under all conditions and workloads. As an example an associate of mine was experiencing problems where they would be working along while listening to internet radio content (work music). Then at some point their CPU would hit redline, the radio playback would begin to skip, the mouse would become sluggish, there would be an overall slow down with whatever application they were using, and the fan could be heard throttling up. Then after five to ten seconds everything would come back to normal. Turned out that their sound card shared the same IRQ as the display chipset, so whenever there was a big demand on the display it had the priority over everything else. When they reassigned the IRQ for the sound card the playback problems went away and everything else behaved. All this while the device manager never registered any conflicts.

I’ll post what I ended up doing to resolve my problem. In the mean time if anyone here is experiencing thermal management problems with their PC here is the web address for “Speedfan”. It’s an open source program that monitors voltages, fan speeds, and temperatures in computers with hardware monitor chips. Speedfan can even access S.M.A.R.T. info for those hard disks that support this feature and show hard disk temperatures too, if supported. The other link will get you to Intel’s support site where people can download manuals, spec sheets, troubleshooting procedures, and the works.

http://www.almico.com/speedfan.php

http://www.intel.com/support/index.htm?iid=hdr+support

notladstyle · Answer

IRQ conflicts are not based on demand, either the problem would be there or would not. An increase in workload wouldnt cause conflicts to pop up and then disapear with the demand. The display in almost all p4 and up dell laptops is not assigned an IRQ. Even maxing out the memory utilization would not cause a slowdown that cooresponded with the cooling fans speed.

Most temperature readouts are in Celcius, not Farhenheight - have you switched yours?

aRenegade · Answer

That may be all well and good; however, I have resolved the problem by manually reassigning the sound card IRQ. The problem I was having was repeatable confirming that it was the problem. No more sudden spikes in the CPU, the fans behaving, no outrageous slowdowns, and the overall performance is back to where it was right out of the box. I hadn't fully grasped the concept that it’s the motherboard (and everything on it) plus the operating system that’s orchestrating the show (so to speak). I was focused on looking for a “culprit” when I should have been looking for “culprits”. This was a system problem, and I was only looking for subsystem answers. I failed to keep an open mind on the cause of the problem. This problem may have been caused by a hardware failure, compatibility problem, improper configuration, software glitch, environment factors, or just plain user error. Many of these may appear as hard problems but are actually something else. Therefore, instead of only checking for faulty components (such as hard drives, floppy drives, power supplies, cables or expansion cards), problems can also be caused by a virus, software that isn’t compatible with a screen saver, CMOS setup program settings, power management features, control panel settings, software drivers, hardware settings, power fluctuations or electromagnetic interference.

Now, Dell motherboards have thermal sensors, that allow users to view the temperature using the CMOS/BIOS setup program or by running a software package such as the Intel Active Monitor or third-party utilities that are available for that purpose. If the motherboard thinks that the processor is running too hot, it will throttle the processor in attempt to cool it. That comes straight from Intel, and reading temperature in Fahrenheit or Celsius is nothing more than a user setting. However, keep in mind sometimes the motherboard may misread the temperature of the processor; but that’s a whole other story.

Anyway, the Mobile Intel 915GM/PM/GMS and 910GML Express chipset family is a graphics memory controller hub (GMCH) designed for use with 90nm process technology based Intel Pentium M Processors (containing 2 MB L2 Cache) and Intel Celeron M processors. It was sharing its IRQ with the sound card. Both devices are high use. When I’m working there are at least a “couple” applications open. There are services running in the background, and I’m connected to the net. All this stuff is graphic intensive and to top it all off, I’m always listening to streaming content (internet radio, subscription music service). So here are two high use devices that Windows assigns to the same IRQ (IRQ 16).

It is possible to share an IRQ among more than one device, but only under limited conditions. If you have two devices that are seldom used, and that you never use them simultaneously, you may be able to have them share an IRQ. Normally, the BIOS assigns unique IRQs to PCI devices. If PCI IRQ Steering is enabled, the BIOS will assign the IRQs to the PCI devices and Windows will typically only change the IRQ settings if it detects a conflict. If there are free IRQs to go around, IRQ Steering allows Windows to assign multiple PCI devices to a single IRQ, thus enabling all the devices in the system to function properly. Without IRQ Steering, Windows will begin to disable devices once it runs out of free IRQs to assign. As best as I can explain, somewhere along the line some third-party utility (optimizer) did something that disrupted the natural order of things. Exactly what is something I’ll leave for someone else to figure out. This whole experience already has caused me enough hair loss, not to mention the pain in my “backside”.

So here we have all this activity, the resources are strained, the processor is doing best it can to keep up with the demand, when that happens the temperature goes up. The motherboard senses that, tells the power supply the fan needs some juice, it kicks in the fan. All of that activity, although high, is not constant, so the fan is throttled, and it’s at those points that the CPU spikes were occurring. The system was doing best it could to keep up with the demands on it by all the running services, processes, and the hardware. That’s the best explanation I have. Whether I’m “right on the money” or “totally off the wall”, the bottom line for me is the problems resolved. Hope this is of help.

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CPU usage suddenly jumps to 100% for no apparent reason

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