Not sure how to label this.

[blueknight1960]

I noticed that when I turn my monitor off, 1 core of the cpu goes to almost 100% usage. Turn the monitor back on and it goes back to normal (which is about 1% same as the other cores.) As far as I can tell, I have no programs open that required the cpu to be used when I'm not doing anything. windows 10 pro w/ the new update. But it was doing this before the update. Any ideas?

 

[habbajabba]

Probably that one new ms theme that they've been working on for the past 30 years.
You could try using a tool such as FileActivityWatch by nirsoft. Probably just explorer or whatever ms calls it now.

 

[Alaric]

W10? Check firewall activity at the time. It probably thinks you aren't looking so it phones home. LOL

 

[S_I_N]

wait how can you tell if the monitor is off??

 

[blueknight1960]

The fans in my system speed up and I use logitech arx control on a tablet so I can see the pc stats when gaming.