So i just made this discovery, which is pretty weird.
I just switched back from Intel to AMD. Namely a Ryzen 9 3900X.
After a fresh install of Windows i installed all my usual software and also Glasswire again.
As i run a custom watercooling loop i also always have a close look on cooling performance.
As you might know, even with a custom waterloop with a lot of radiator space, idle temps of the 3900x will be in the high 40s to low 50s when idle in Windows. That´s perfectly normal.
BUT i was seing idle temps of low to high 60s (with spikes to low 70s even), which is NOT normal.
So i began to investigate. At first i thought my waterloop monitoring software was to blame as there can be issues with the CPU missinterpreting monitoring tools as a high load and thus raising voltage and clocks.
In the end this was not the case. So i had a closer look at software i installed recently, as right after the install, temperatures were perfectly fine.
Looking at task manager i then saw the GlassWire Control Service constantly using 2 to 3% of CPU.
This doesn´t look like much but made me suspicious.
So i quit the Glasswire GUI and ended the Control Service process from task manager. And, would you believe it, my temparatures instantly dropped down to the mid 40s again with the usual fluctuations.
I don´t know why this happens but in my case Glasswire is definitely the culprit of the 3900x high idle temps and i will need to stop using it for now.
I can perfectly reproduce this issue on my machine. If i should test something to help fix this issue, just let me know.