CPU Spiking When Computer Is Locked

Today I installed a new CPU cooler onto my desktop that actively monitors the CPU temps and will adjust the fan speeds as needed. It also alters an LED on the cooler based on the temps of the CPU.

I noticed now with this new cooler that when I lock my system and let the screen timeout and turn off, the CPU usage will spike and stay spiked until I activate the system again by touching the mouse or hitting a key to turn the monitor back on. At that point, it will stop spiking and normal out.

Looking around for some solutions to this, most people that had similar issues resulted in having an ASRock motherboard with an application issue, I, however, have a Gigabyte board with no special software for it installed.

My system has not changed other than the cooler and the case it is in since the last time it was turned on so this is something that has apparently been going on prior and this new cooler is now making me aware of it.

I'm not sure what would be causing this. I have tried monitoring the processes while the system goes into its 'idle' state with the lock screen on and the monitors auto-turning off.

For example here is a screenshot from procmon.exe showing CPU usage in a small time-frame from when the screen timed out til I rewoke it:

MsMpEng.exe seems to be the culprit. At the highest peak, it was at 28% CPU usage which ProcMon says was a 'Process Profiling' operating. Basically every event seems to be listed as 'Process Profiling' for it while the screen is off yet the CPU is hitting 20-30% consistently soon as the screen turns off.

Does anyone know why this would be happening, and how to stop it? I don't want my system to be trucking along while it's not in use and I do not want to turn it off between usage as there are some programs I do want running in the background (messaging related things) in case I got something important.

Edit :: Using 'Remote Process Explorer' I confirmed it is definitely MsMpEng.exe hitting the CPU to 30% and holding it there while the screen has turned off. I disabled 'Real Time Protection' and this does not seem to help prevent it from happening. Is there a way to stop this behaviour without completely disabling Windows Defender?

user108160

Posted 2016-03-16T09:27:18.483

Reputation:

Can you confirm the CPU wasn't running at 30% before you changed the cooler? Honestly my guess is that your other cooler did exactly the same thing, but it was quieter, so you didn't notice it. "MsMpEng.exe is a core process of Windows Defender, which is Microsoft's antispyware utility." - So Windows Defender is doing a scan when your system is locked, likely as it was always configured to do, you just never noticed. – Ramhound – 2016-03-16T16:59:12.070

Answers

This is the idle maintenance task, that kicks up when Windows is idle.

To disable it, run Task Scheduler, go to

Task Scheduler -> Microsoft -> Windows -> Task Scheduler

Here you have to right click on the Idle Maintenance and select the option disable.

enter image description here

In Windows 10 the task is called RunFullMemoryDiagnostics under Microsoft > Windows > MemoryDiagnostic > RunFullMemoryDiagnostic.

magicandre1981

Posted 2016-03-16T09:27:18.483

Reputation: 86 560

I don't have my Windows 8.1 or Windows 10 machines handy, can you confirm that part of the idle maintenance, is defender starting a system scan? – Ramhound – 2016-03-16T17:06:42.240

I also see MsMpEng.exe running, so it seam to do some short scans. – magicandre1981 – 2016-03-16T17:26:15.830

1Killing the idle maintenance got rid of the CPU spiking and MsMpEng.exe no longer runs everytime the system idles. Thanks! Something I did notice is that after a while it will stop and be finished its maintenance cycle. However, if I log back into the system and put it back into idle mode it will instantly start up again. If it just finished the same task minutes ago, why does it restart and do the same thing over and over each idle.. That seems very counter-productive and harmful to hardware, especially SSD's. – None – 2016-03-16T18:47:12.267

The computer is idling so it launches applications and services to do maintenance - defragment and optimize the drives and check for malware which is done by Windows Defender, MsMpEng.exe, to be exact. I see no issues here.

Little Helper

Posted 2016-03-16T09:27:18.483

Reputation: 1 906

I run SSD's so defragging is not something that is automated. Real Time Protection is disabled in Windows Defender and this behaviour continues. This is not normal and is definitely an issue idling my CPU to 30%. – None – 2016-03-16T10:19:25.343