What is causing my computer to slow down and how can I fix it?

[CRGreathouse]

I'm running Windows XP on a dual-core notebook and I noticed that sometimes (like now ;)) the computer slows down dramatically as though under heavy load, but the task manager reports nothing: the system idle process claims 97% of the CPU and there's only ~500 MB of RAM in use (on a 2 GB system). But the fans run loudly, and the task maanger does report (in a contradictory way) that CPU usage is about 55%.

Any thought? I do have "show processes from all users" checked.

 

[robphy]

Have you tried "Process Explorer"?
http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

 

[Borek]

It is just a wild guess, but if the fans run, perhaps your notebook is overheated so it automagically slows down? I was never interested in details but some processors (especially those targeted at notebooks) have fancy solutions implemented to save on energy and to diminish chances of overheating.

 

[CRGreathouse]

The laptop does have automagic slowdown (Intel's SpeedStep), but it wasn't on at that time.

Process Explorer may have found the problem. For a decent chunk of time, maybe two minutes, there was 40-50% CPU use for "hardware interrupts". Should they really take that much juice?

 

[robphy]

On occasion, I have an issue with my setup in which the Bluetooth drivers are trying to install devices it detected [which I don't want it do]. This eats up my CPU time as it struggles to install these devices. So, I have to manually kill off the process. (If I allow it to finish, the install eventually fails... so I kill it off early.)

So, something like this might be an issue.
Is there a particular process that is using up the CPU? Process Explorer can help identify the process.

 

[CRGreathouse]

So, something like this might be an issue.
Is there a particular process that is using up the CPU? Process Explorer can help identify the process.

Process Explorer calls the process that I identified above "hardware interrupts".

 

[robphy]

Process Explorer calls the process that I identified above "hardware interrupts".

possibly useful discussions:
http://forum.sysinternals.com/forum_posts.asp?TID=2064
http://forum.sysinternals.com/forum_posts.asp?TID=7775
http://forums.tweakguides.com/showthread.php?t=3733

 

[CRGreathouse]

Thanks, I'll look into that.

 

[MeJennifer]

But the fans run loudly, and the task maanger does report (in a contradictory way) that CPU usage is about 55%.

Since you have two CPUs that likely means that one of the cores is running 100% running a single threaded job.

 

[CRGreathouse]

Since you have two CPUs that likely means that one of the cores is running 100% running a single threaded job.

Yes, certainly. That's why I mentioned that I was a running dual-core.

 

[CRGreathouse]

http://forum.sysinternals.com/forum_posts.asp?TID=7775

That did it for me! Or at least found the problem, which I trust I can fix. My hard drive went from DMA to PIO mode, so every time I used the hard drive everything slowed down.

I'm playing with
HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 0\DMAEnabled
now; hopefully this works.

 

[CRGreathouse]

OK, it's solved. I deleted the driver for the primary IDE and rebooted twice. Now the hard drive is back to DMA and the computer is running at least four times faster.

Thanks a lot, robphy!

 

[mgb_phys]

There is a 'feature' of windows from XP onwards, after a certain number of drive errors it automatically switches to PIO mode.
This is a problem with DVDs, if you play a badly scratched disk it assumes the errors are due to the drive and switches to PIO which is often too slow to play movies.

See http://sniptools.com/vault/getting-back-to-dma-mode-in-windows-xp to fix it.

 

[russ_watters]

Ouch, that's good to know - I noticed my dvd drive running rediculously slow a few months ago and found it in PIO mode. Gotta love MS! What they should do instead is slow down the rotation of the disk, try to read the area a few times at a lower speed, then decide it is a disk error.

 

[CRGreathouse]

There is a 'feature' of windows from XP onwards, after a certain number of drive errors it automatically switches to PIO mode.
This is a problem with DVDs, if you play a badly scratched disk it assumes the errors are due to the drive and switches to PIO which is often too slow to play movies.

See http://sniptools.com/vault/getting-back-to-dma-mode-in-windows-xp to fix it.

Yes, this is an intentional feature -- though I thought it started in Win2000, not XP. Regardless, I happened to try that set of steps (though I didn't read that page) and they failed for me. Only deleting the driver worked.