Helping people with computers... one answer at a time.
Can a computer really do nothing? Yes and no. When it's doing nothing it has to do something, and that something is the System Idle Process.
What is the System Idle Process and why is it using 96 to 99% of the CPU?
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This is a great example of things we geeks probably take for granted, that's not always obvious to the rest of the world.
I mean, really, a process that regularly takes up 99% of your CPU's time must be a bad thing, right?
Nope, not at all. Just the opposite, in this case.
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First, let me show you what we're talking about.
Firing up Windows Task Manager, and then clicking on the "CPU" column to sort by CPU Usage, (click again to reverse the sort order if all you see are zeros in that column) you'll often see something like this:
You can see that something called "System Idle Process" is taking up a full 92% of my CPU's resources.
Seems like a lot, so what's up with that?
The fact is that most computers can never really do nothing. When the computer is on, the CPU's running and it must do something - even if that "something" is waiting for something real to do.
Think of it as your computer just twiddling its virtual thumbs, waiting for something more important to do. The computer's doing something (virtual thumb twiddling), but we wouldn't call that doing anything useful.
That's called being idle.
And the "System Idle Process" is the software that runs when the computer has absolutely nothing better to do.
It effectively runs at the lowest possible priority so that if anything, anything at all, comes along for the CPU to work on, it can. When there's nothing left to do, back to idle it goes.
So having the System Idle Process using 90% of your CPU is a good thing ... it means that that 90% is readily availble should there be any real work to do.
Article C3322 - March 17, 2008 « »
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.
December 30, 2009 4:27 PM
Leo from reading the posts i belive what the folks who are having trouble with System Idle Process are trying to say is their computer is not switching over from idle . Like say you start IE and their system does not send CPU to IE it just keeps at idle .
If i was one with that problem i would click on the Performance tab then see the real time CPU Usage even if System Idle Process is at 99% it should read very low if not zero you may see a bounce but that is other stuff running
January 31, 2010 7:46 AM
how do I get it to stop when I want it to so I can do other things like close and open tabs and search, etc.
March 30, 2010 9:20 PM
the system idle process takes up all my cpu and wont switch over and everything is slow what do i do!?!?!
March 31, 2010 8:45 AM
Ken, I'm having the same problem. With nothing open, my SIP is still at 98 to 99% and EVERYTHING is slow. There has to be something to this. Can I just "end process"?
01-Apr-2010
April 1, 2010 12:39 PM
System Idle Process is your computer DOING NOTHING. Your CPU is *idle*, hence the name.
If you're experiencing system slowness while the System Idle Process is "running" at high percentages, System Idle Process is not the problem. More than likely some other component of your system - often the hard drive or internet connection - is experiencing difficulties that manifest as overall slowdown.
Again: System Idle Process is not the problem. A high "usage" of System Idle Process tells you that your CPU has nothing to do, and that you should look elsewhere for the problem.
01-Apr-2010