ROG Z390-F auto wake up of the fans

[Rombo]

Hi,
I have a strange and annoying problem that I was unable to solve.
I have read many forums on Win10, but no suggestions have solved the problem.
I hope to find here some ideas.
I use the PC for work, no games, no overclocking.
I have disabled anything that can wake up the PC when it is in sleep.
When the PC goes to sleep, after a few minutes, sometimes even less than one,
the fans start, sometimes at maximum speed, and then, after a few minutes, they turn off.
Nothing happens on the monitors, windows does not wake up.
The HDD LED flashes. This should mean that Win10 is involved.
After a few minutes the story begins again.
The stranger thing is that all this does not always happen.
Every 3-4 days, the PC works well, goes to sleep and wakes up only when I press a button on the keyboard.
My system consists of: Win 10 Pro, ROG STRIX Z390-F, i7-9700K, 16G DDR4, Radeon RX590, 2x SSD 1TB.
Has anyone had a similar problem?
Thanks
Rombo

[Rombo]

I forgot the case, Sharkoon TG5 with 4 fans.

[davemon50]

Suggest your first move is when you see the behavior again, immediately check your Windows logs to see what events have just occurred. They are usually very cryptic and unhelpful, but sometimes it provides you an avenue to investigate.

Also, have you been looking at the Windows Task Manager at all to see what's been using resources?

Is this case fans only, or CPU fan if you have a dedicated one, or any other fans, or just every fan in your system? And you said sometimes at max speed, so does that mean that they ramp under control sometimes?

[Rombo]

Hi Davemon50, thanks for your reply.

I have never seen the event viewer. I'll try to see if I understand something.
The problem occurs even if no programs are open.
The fans are 3 front and 1 rear. They are powered in PWM by the Mother Board and therefore the speed is variable.
This is why I think it may be the MB.

[davemon50]

Is your power plan custom, or are you using one of the defaults? For advanced options under your power plan, do you have the wake timers disabled under the Sleep section?

[Rombo]

No, timers weren't disabled!
Now I try and let you know.
Thanks

[davemon50]

W10 power options are horribly intrusive. Even if you had them disabled before, I find Windows resets my power options periodically. Infrequently, but it has been done. That's why I asked about yours.

[Rombo]

Problem solved!
If it were to repeat, now I know where to look.
Thanks davemon50

[davemon50]

Good stuff, thanks for reporting the solution.