The problem seems easy at the first glance but is a little more complicated. The machine (Lenovo laptop) has Windows 8 Pro, a Intel Core i7 and all 4 cores run at 100% . The fan runs at full speed the whole time. When rebooting the fan spins down and starts to spin up once the start screen comes up. I tried to kill all unneded processes but it had no effect, there is also no additional anti virus software installed.
In the task manager the System Idle Process is shown with 98%-99% as well as in procmon ( sysinternals ).
I am pretty sure that the idle process is not the root cause, but there has to be one and the only thing changed were windows updates including a new driver for the integrated intel graphics card. This could have something to do with it but the high cpu load didn't start until I put the device to sleep and woke it up a few times.
I also don't want a quick solution to the problem but rather find out what causes it, any ideas are appreciated
UPDATE 1: I ran xperf to gather more detailed information:
xperf -on latency -maxfile 256 -filemode circular xperf -d trace.etl xperf trace.etl
The CPU usage in the graphs is normal, a few spikes but average cpu usage. To me it seems this problem is caused by the system thinking there is a high CPU load ( which shows everywhere in windows ( taskman, procmon, perfmon )) and therefore spinning up the fan. I have to look at the CPU temparature to verify, if this is the main cause I only have to find out who spins up the fan, this could be windows but also a lenovo driver
Update 2: Okay this is critical as the CPU temp is constantly at 110°C so something really does cause the CPU to work
Update 3: The heavy load doens't occur with Windows 7 and already starts at the login screen of Windows 8