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What this normally means is that there is some software on your computer that is essentially trying to hog all the CPU.

Sometimes, my computer sounds as if it's running away. When it does this, the cursor freezes and I can't do anything until it slows down. I don't know if this is the hard drive going bad or another problem.

In this excerpt from Answercast #55, I look at a noisy machine and how to find the process that is causing the fan to roar.

Loud computer

In my experience, what this normally means is that there is some software on your computer that is essentially hogging the computer. It's trying to use all of the CPU and is actually preventing the other software on your machine (including the software that, for example, would handle your mouse or keyboard) prevents that software from even running, and from being able to update the mouse position or accept your keystrokes.

The reason it sounds like it's running away is usually related to heat.

The computer fan

Most computers these days run the fan slowly to keep the computer cool while you're using it normally.

Most of the time your computer's processor actually isn't doing that much. Just typing an email or looking at a web page doesn't really require a lot of horsepower. A lot of the time, while you're doing what you would normally do on your computer, the CPU is actually spending most of its time doing nothing.

Doing "nothing," it can do at a very low temperature.

On the other hand, when software comes along that tries to use the CPU intensively, and for long periods of time, then the CPU gets busy. When it gets busy, it gets hot - and when your CPU gets hot, what happens is the system kicks in the fans at a much higher speed to move a lot more air across the processor to try and keep it cool.

Cooling the CPU

You and I hear that as the fans speeding up. Sometimes, they go right into max speed and you hear these fans blowing a tremendous amount of air through your computer in an attempt to keep the CPU from overheating.

So, it's a good thing in that your computer is keeping the CPU from overheating. It's designed to do that. But, as you can tell, it's a symptom of your CPU being used at its max capacity. It's generating a lot of heat.

What's using your CPU?

What I would suggest you do when you encounter this, there's an article I've got about "What is hogging all my CPU?" That will actually walk you through grabbing a copy of a program called "Process Explorer," and using Process Explorer to see which process on your computer is actually using the CPU at the time you discover this problem.

Most of the time when things are running normally, you will find that the processor is running a process called "System idle." And that's as it should be.

The System idle process is the process that essentially does nothing. The computer is idling. It actually goes into a low power state at the CPU level so it's not generating a lot of heat.

Analyze your CPU usage

As soon as a program comes along that tries to use the processor excessively, you'll see that bubble to the top of the list in Process Explorer, and you'll be able to quickly identify at least what process it is.

From that, you'll have a clue what to look at next:

  • It may be a program you're expecting. In which case, you may be able to do something about it.

  • It may be something you're not expecting. In which case, perhaps you'll have to research it a little bit further.

But you'll have that data that says, "OK, this is the program that's causing the problem. Now, let's see what we can do."

Article C5842 - September 23, 2012 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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1 Comment
David B
September 23, 2012 3:49 PM

If a computer hasn't been cleaned, then dust bunnies could be clogging the fans, and acting as a blanket - both of which stop the heat from being vented properly. A thorough house-cleaning, to remove dust build-up, can not only reduce the noise from a computer, but extend its lifespan dramatically.

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