Slow PC, but low CPU usage?

Today I was working on a slow PC that hung intermittently doing various things, but the hanging did not appear to be related to CPU usage.

What does this suggest? What else (besides cpu usage) could cause this sluggish performance?

I know memory leak is one answer.  Any others I should be aware of?
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What about disk usage? Try a chkdsk /R?
Lee W, MVPTechnology and Business Process AdvisorCommented:
Not just memory leak, but inadaquate RAM.  Also, I've seen Video Drivers cause serious slowdown problems on some systems - mostly when the driver is not installed and windows is using basic drivers.
Juan OcasioApplication DeveloperCommented:
I would agree with leew.  The problem seems to be not enough memory.  The intermitent hangs is usually an indication of the memory being filled up and the programs running going to your swap file to access 'more' memory.  What happens is the OS swaps out data on disk as it's needed and this cause a huge lag and degredation in performance.  A couple of things can be done:

Defrag the drive.  Before you do this, turn off the swap so the space can be drefraged as well.

Add more memory.  probably your best bet



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What is the config? OS, RAM, CPU, etc.
Jeff BeckhamEngineerCommented:
A memory leaks cause problems over time and are always fixed with a reboot of the machine.  Immediately after the reboot, things are fine and they deteriorate slowly until the OS dies or the machine becomes unbearbly slow.

Some things that could make functioning hardware slow: old/underpowered hardware, insufficient RAM, low disk space, spyware/virus software, incorrect/outdated drivers, paging file too small, malfunctioning hardware, lots of things.

It could also be faulty hardware, hard drive being the most likely culprit.

It's really just guessing based on the information you provided in your question.
Slow PC, as you mentioned about memory leak, is one possibility.

Some programs are poorly written, once the program is closed the memory space used sometimes do not get released and does not become available for other processes.

Sometimes temporary files running in the background consume system resources, obviously, not just the CPU usage. I run CCleaner (, usually after I use resource hungry applications. Though it does not directly remedies these issues but it does free up some space and a few other things that sometimes affect the system performance.

Another reason, main one I believe, would be that you have low or just above recommended amount of RAM. Things are running just fine when you have a lot of space on your HDD for page files / virtual memory.

It's when you run low on HDD space that lack of adequate (I personally see 512MB of RAM as in adequate amount of memory if you run high end applications) physical memory. We run Pentium III 1GHz+ computers at our office, which is good enough for everyday apps. But having low physical memory have affected us a fair bit.

If you HDD gets more noisy than usual, then it could be the above issues, or the HDD is reaching the end of it's life.

There are a lot more of other reasons but I'll leave it at that.
chack also this : is your disk (and cd) not reverted to PIO instead of DMA?
check in device manager, ide /Atapi channels primary channel>advanced tab
Also heat can cause it : if the cpu gets too hot, the frequency steps down, so check the temperature of the cpu, and if all fans are running, clean off any dust
Check your page file usage available memory in Task Manager when one of these slow downs happens. What are the various things that slow down your computer? If you see your memory low and page files usage high. Try closing programs to see which program that when you close it frees up the most memory. If closing all the programs doesn't free up to much memory then you have a back ground program or service casuing this issue. If it happens when you downloading a large (>5MB) or large emails then it maybe your AV software using alot of memory to scan the incoming file. I have had this happen with a couple of different AV software. The most recent is EZ-trust. Which when a large email was coming in would literally take up 300-400MB of memory.
Dushan De SilvaTechnology ArchitectCommented:
Chekc your Virtual Memory is enough.

And try with

BR Dushan
Some services may be running underground you can reduce this by using msconfig to free resources.

Hard disk space may be running out

Hardware specifications do not meet or barely meets the required specs of the OS and other software used.

CPU fan may not be rotating properly

among several others....
Then there is a possibility of wrong motherboard drivers and bios versions...I was running, well am, a dual core intel and I had nothing but slow response and cpu was never taxed. Just everything ran bad. After I redid all the drivers and updated the bios the machine ran fine. Now it is a workhorse. I would agree if you are running a low amount of ram with an equally small virtual memory file, your machine will get slower and slower. I have worked on numerous systems with XP with low memory and it is amazing how a defrag, cleanup, and addition of memory makes a big difference. Of course, you must also verify that you don't have any background friends running and making your life difficult. Spyware, adware, trojans, worms, and bears...oh my...

Computers have been known to run slower if some harware are not working right such as the cd rom
dgrrrAuthor Commented:
to Markmems --

what is the relation between chkdsk /r and "disk usage"?  And are these similar to "sfc /scannow"? (check OS files)
dgrrrAuthor Commented:
Leew - Can I rule out the video driver IF AND WHEN device manager is happy with the video drivers, and displays the device name (model/brand) and shows no alerts?that aren't central to the problem)


(1) Can Spyware slowdown the PC by eating memory, without eating CPU?

(2) bonehead question -- do running SERVICES appear in TAsk Manager, as some kind of process? SVCHOST?

(3) The general wisdom on page file size settings is still -- XP and beyond - let system manage. Pre XP - 2:1 ratio, Pagefile:RAM?

(1) Yes.  If its taking up RAM then there's less RAM for other applications to use.


(3) Yes. Generally let XP manage RAM.

You don't specify your CPU and RAM settings and applications you are running.  

128  Mb is adequate.
256 Mb and more is far better.  These are rough guidelines.
dgrrrAuthor Commented:
dbrunton - these questions are for my general knowledge, hence no specific hardware figures (ram, cpu)
Disk usage - You don't want your drives over 75% full.
Chkdsk /R - Just repairs (or marks) physical disk errors, if any.
Also see jocasio's tip on defrag.
Give XP a Gig. It's cheep! We tell our customers 512MB min.
dgrrrAuthor Commented:
Memory's cheap - unless you bought a rambus computer, lol!  (it's the "matching pairs" limitatin that gets you, lol)

OK, I get the his meaning of "disk usage" now.  But -- Do any of the above fixes / indicators correspond to EXCESSIVE HARD DRIVE ACCESS?  (aside from Virtual Memory)?
e.g. I was working on a pc today, and for some reason, the Netgear Wireless Config Util was constantly accessing the drive, no memory or cpu usage tho...  Is there an indicator of this one?
Open Task Manager and go to the Performance tab. Physical Memory - Total should be greater than Commit Charge - Total. Otherwise, you dn't have enough RAM and your disk is being hammered by paging.

If you want to get advanced, run perfmon and watch some counters. Look at PhysicalDisk and Process.
Mohammed HamadaSenior IT ConsultantCommented:
Hello Dgrr....

Have you tried to track your computer startup process ? maybe you will notice by anyhow the error and where is it existed weather is it a hardware related or software, Try using Bootvis....

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