Interesting 9900k idle temps issue

[ancientmariner]

I have noticed an interesting issue with my system recently, my idle temps are fluctuating in the 60's for apparently no reason. With nothing other than windows running i am seeing fluctuations all over the 50 and 60's. Since i built the system last year idle temps would not exceed 40. This recent issue seems utterly intermittent and once i reboot all is fine again. Running a 9900k at stock speeds with 1.265 vcore under a H100i.

I am putting the blame firmly on Windows at this stage, but rather than reinstall, any suggestions as to what may be causing this?

 

[DarrenM343]

I wouldn't put the blame firmly on Windows 10 until you know what's causing it.
Only thing I can think of at the moment is to check what processes are running when this happens via task manager, possibly killing off some active ones that you're unsure about, whether they need to be running or not, and then checking temps again.
Check when it starts happening too, ie, how long after reboot and what you might be doing at the time (what apps recently started).
Could easily be a bug in something you have installed, including drivers, or even mobo bios.
Windows isn't without it's bugs, as a large complex system, a lot of them people won't come across, but something like this would likely be common knowledge and fixed pretty soon, if it is indeed Windows.