Question

On Windows 7, the 'system' process is taking up 100% CPU (well 50% on a duel core) for a rather long time. Its CPU usage doesn't seem to drop at all.

How can I diagnose this problem? What could be the cause? I don't see any other problems with the system and am using an up-to-date AVG, so I don't yet suspect a maelware.

Answer 1

You first need to find out which system process it is. Go to Task Manager, Processes tab, and click twice on the column "CPU Time" to sort descending (if it's not there, add it from the menu View / Select columns...).

If it's by any chance the "System Idle Process", then this is quite normal.

If not, right-click on the system process and choose "Go to service(s)". This will open the Services tab and highlight one or more services. Please include their names (or a screenshot) in your post for us to see.

Answer 2

Modern Antiviruses are a little rubbish, don't assume you're fine because you've got one (though they can help)

The System process taking up an entire core shouts "Driver issues!" quite loudly to me, anything been updated or changed recently? Any devices showing a bit iffy in Device Manager?

Grab a copy of Process Explorer and take a look at what it's doing in a little closer detail.

Answer 3

This could be a process doing heavy I/O. Since that is performed by the System "process" you would see the CPU usage spike there.

I've once had that with the IDE controller reverting itself to PIO mode. Though that was on an ancient system, dunno whether that even happens anymore with modern OSes :-)

Also don't forget that AV software can even cause this themselves. It's not uncommon for them being a performance problem :-)

Answer 4

There is this interesting article, if you'd wanted to know what exactly is causing it.