I've had my XPS 12 since January and I have been having high cpu when the system goes idle to screen saver.
Problem Process: System, ntoskrnl.exe
I re-installed every driver and was able to eliminate a driver issue for my situation and also disabled AV. Even after this, I was still receiving high CPU when my system would go idle.
I finally figured out the reason why. I discovered that my high cpu occurs when I either unplug my machine from AC power or when I plug my machine back into AC power when Windows 8 is running.
I am not sure what is exactly causing this, but I use balanced on battery and max. power on AC.
However, now when I go on or off AC, I make sure the laptop is off and then turn it back on when I plug it in or unplug it.
Sounds dumb, but I haven't had an issue since I implemented this process.
Hope this helps someone, because I wasn't able to find anything.
-Kevin
