CPU idle in Windows 10 goes from 5-10% to 30-40% after a few minutes.

[eclap]

See topic...

So I could be just browsing and watching some YouTube, my CPU usage will sit under 10%, usually around 5% no matter what. CPU temp is around 30C.

But after a few minutes, something like 10-15 minutes, the CPU usage goes up to 30-40% for no apparent reason and the CPU temp is now around 50C.

I only noticed this today as I heard the CPU fans spin up a little bit so I thought I'd check task manager to see what's stressing the CPU. To my surprise, as soon as I opened the task manager, the CPU usage and temps went straight back to the initial values.

I've been able to reproduce it over and over after I discovered this. Leave the PC in idle, doing no taxing tasks and every time after about 10-15 minutes, CPU usage/temps go up until I open the task manager.

I've ran various scans, Defender, Malwarebytes, Malwarebytes ADW, Hitman PRO, none of them found anything. Hitman PRO flagged up some cookies but the behaviour still prevails even after deleting these cookies.

Is this normal behaviour? What could be causing this? I usually wear headphones and have either YouTube or music on so it would be hard for me to spot this happen, this could have been going on for weeks for all I know.

Any advice will be highly appreciated. Oh btw, the PC performs as expected, games run great, no crashes, no silly popups. Had it not been for me catching the fans spin up a touch earlier today, I wouldn't even know this is happening.

EDIT: Just happened again... Heard the fans spin up again so checked MSI Afterburner monitoring and you can see how there's a jump in usage and temps. After I just opened task manager, everything drops back down to the low values...

EDIT2: This is what happens after I open task manager, usage and temps drop for 10-15 minutes until the thing happens again.

 

[Zefan]

If you're worried about something listening for task manager to be started, you could try sniffing about using resource monitor instead. You could try investigating in cmd, using tasklist to show all running processes or typeperf to interrogate the CPU usage (Google). For powershell you could use get-process to show running processes, or get-counter of some variety (Google) to show cpu usage.

:edit: another fun tool https://docs.microsoft.com/en-us/sysinternals/downloads/procmon

 

[Rroff]

Possible malware but Windows 10 does a lot of maintenance, prep tasks for pending Windows updates, etc. in the background when it "thinks" the OS is idle (or sometimes whenever it wants) - I'm surprised more people don't complain about it. Some of it will stop when activity is detected.

When your system usage patterns are like mine it is a complete pain in the rear - I'm guessing it is less noticeable for people who generally just do average desktop stuff and leave their PC on for many hours a day unattended actually idle, etc.

You may be able to identify what processes are doing it from looking at CPU time levels, etc.

 

[eclap]

If you're worried about something listening for task manager to be started, you could try sniffing about using resource monitor instead. You could try investigating in cmd, using tasklist to show all running processes or typeperf to interrogate the CPU usage (Google). For powershell you could use get-process to show running processes, or get-counter of some variety (Google) to show cpu usage.

:edit: another fun tool https://docs.microsoft.com/en-us/sysinternals/downloads/procmon

Forgot to mention, opening resource monitor acts exactly the same as opening task manager. I honestly don't know if it's malware, I'm very cautious about where I go on the internet and what I put on my PC. Plus none of the anti malware scans I used came up with anything. Maybe I'm just worrying about something superficial.

Will have to do some digging.

 

[eclap]

So last night I tried something... I waited for the cpu usage to go up in Windows again and then fired up Assetto Corsa Competizione. Sitting on the grid, my CPU usage was pretty much pinned to 100%. The game ran fine though. But I thought I'd open task manager and yep, the CPU usage now dropped to around 60%. So clearly there was something shady going on in the background.

So at midnight I decided to re-install Windows. Just about have it all set up and will keep an eye on things throughout the day.

Can I just say that installing Windows on a NVME drive is always such a pita. Fingers crossed, this will now fix the issue.

 

[Donnie Fisher]

Not necessarily. As already mentioned, windows will churn and run maintenance in the background. Windows defender scanning, indexing, downloading updates etc etc , it all happens in the background when it thinks you’re not doing anything. As soon as you open the likes of task manager, windows immediately thinks that you aren’t idle anymore as it’s been a user driven event.

As for the game, that’s different. When you drop out of the game to task manager, you are suddenly not needing to run the CpU at 100 percent as it’s now a background process.

I think you are worrying about nothing to be honest, and it’s just windows doing it’s thing.

 

[eclap]

Not necessarily. As already mentioned, windows will churn and run maintenance in the background. Windows defender scanning, indexing, downloading updates etc etc , it all happens in the background when it thinks you’re not doing anything. As soon as you open the likes of task manager, windows immediately thinks that you aren’t idle anymore as it’s been a user driven event.

As for the game, that’s different. When you drop out of the game to task manager, you are suddenly not needing to run the CPU at 100 percent as it’s now a background process.

I think you are worrying about nothing to be honest, and it’s just windows doing it’s thing.

Ok, so I've been running the PC all day, mostly in "idle" just installing bits and bobs. No more weird behaviour.

With ACC, like I said, the CPU usage was at 100% and after I opened the Task Manager, it went down to 60% or so. But it also stayed there. Also surely, running a fairly demanding game should give Windows heads up that I'm doing something. But it's only task manager that dropped my CPU usage. Every time.

I don't know, I'm still confused about it because everything ran well and I couldn't find any traces of any malware etc. I've been building PCs since the mid 90s and I know my way around a PC, also am careful about what I put on my rig. Not to be big headed, just saying I'm not someone who's completely new to PCs.

Still, it was time to re-install Windows anyway, the install was close to 2 years old so a fresh start was overdue. This install will carry me until I upgrade the core of the system, when DDR5 becomes mainstream.

 

[Rroff]

Also surely, running a fairly demanding game should give Windows heads up that I'm doing something.

Windows 10 is pretty glitchy when it comes to identifying when the system is actually idle or not - for some people it works OK for others it is very hit and miss.

Another one I've found can be a problem is Windows Defender getting itself stuck in a definitions update loop but usually that just sits there using ~40% CPU all the time rather than depending on activity level. Some stuff in Windows 10 will fail and re-try in the background constantly though while also being triggered by activity level so possible an update or other task was in a stuck state.

 

[eclap]

Windows 10 is pretty glitchy when it comes to identifying when the system is actually idle or not - for some people it works OK for others it is very hit and miss.

Another one I've found can be a problem is Windows Defender getting itself stuck in a definitions update loop but usually that just sits there using ~40% CPU all the time rather than depending on activity level. Some stuff in Windows 10 will fail and re-try in the background constantly though while also being triggered by activity level so possible an update or other task was in a stuck state.

Interesting. It's true that I've usually treated Windows as something you install and keep updated and it takes care of itself as long as you're not an idiot. Perhaps I just picked up on something misbehaving. But, and I don't know if it's the same for many of you guys, if I pick up on something fishy, it has to go so I re-installed Windows and the behaviour is gone. For now, it could still come back.

I've googled this a lot yesterday and there's countless threads about this sort of behaviour. So it's probably pretty standard. Still, thank you all for your input. This forum rocks, didn't expect so much advice in such a short time to be honest.

 

[Donnie Fisher]

A new install of windows will churn a lot for a few days in the background. It installs quickly and gets up and running but then runs a lot of tidy up maintenance for a while, indexing and also things like monitoring what files it needs most regularly and arranges them about for the fastest access * at boot time.

* it did this with HDD drives, not sure whether it does it on SSD tho .


Generally though, I wouldn’t worry about it. You’ve seen that as soon as you ask the machine to do something, t gives up whatever it is doing and gives you all it can, only going back to the background tasks after the 10 min wait that you’re seeing. So it’s really not interfering with your use of the machine.

 

[eclap]

You’ve seen that as soon as you ask the machine to do something, t gives up whatever it is doing and gives you all it can, only going back to the background tasks after the 10 min wait that you’re seeing. So it’s really not interfering with your use of the machine.

Well, almost. It's only Task Manager that made the CPU usage drop. Running a demanding game didn't drop CPU usage. And from what I've read, a lot of Malware looks out for Task Manager. It'll run in the background until you open it and then it immediately kills all the processes.

It's weird and I couldn't detect any malware running so maybe I'm paranoid but a fresh Windows install resulted in no such behaviour. So far I have been online streaming football and watching YouTube while browsing the net and no funny CPU usage behaviour to be seen.

I'm not saying you're wrong and I swear if I see this behaviour again in the next few days, I'll just put it down to "things Windows10 does". But if it happens, I think I'll sleep just fine thanks to you guys' advice.