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System Idle Process high CPU? Don't worry, it's normal

Worried that your PC is burning itself out by running the System Idle Process? Don't worry, it's a normal part of Windows

File Manager

Windows Task Manager is a brilliant way to see what's going on with your computer, but it's also a little scary to see what's eating up your system resources. In particular, you may notice that there's a task called System Idle Process, which can be taking anything up to 99 percent of your CPU's time. So, what's going on, is your computer affected by malware, or is it just burning itself out for no reason?

It's nothing to worry about

The simple answer is, none of the above. The System Idle Process is, as the name suggests, just a measure of how much free processor time your computer currently has. So, if System Idle Process is taking up 99 percent of your CPU's time, this means that your CPU is only using one percent of its processing capability to run actual tasks.

So, why do this instead of just showing zero usage? Well, there are two main reasons. The first is that this helps the task scheduler run, as without this process there may be a time when the task scheduler wouldn't be able to find a CPU core to run a new thread on.

Secondly, the System Idle Process can be used to run specific power-saving tasks. For example, it can be used to shut down parts of a CPU that aren't currently being used; when a 'real' task comes in, the CPU wakes up all of its parts.

As processors have become more complicated and more efficient, the System Idle Process has also improved. So, it can now reduce processor clock speed and implement other power saving options.

How to check System Idle Process

To see the System Idle Process in action depends on the OS that you're running. In Windows 10 start the Task Manager (press CTRL-SHIFT-ESC) and click on the Details tab. Sort by CPU when your PC isn't doing much and the System Idle Process should be at the top 'using' most of your CPU's resources.

In Windows 7 and Windows 8 start the Task manager (press CTRL-SHIFT-ESC), tick the 'Show processes from all users' box and click the CPU header to sort the list. The System Idle Process should be at the top when your computer's not very busy.

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