Since a while a saw the processor temperature running on critical levels. I use a Thinkpad W520 since three years now. Since I installed Plasma 5 the temperature in idle condition is around 70°, if I am happy 65°. But after using it a while it gets up to 90° or even 95°, with a processor use of maybe 10-20% and doing nothing demanding. 

I was very reluctant to change anything, but after one year being afraid that running on this high temperatures will not be good for the hardware I finally decided to use Cinnamon to test, if there is the same problem occuring. Here I get temperatures around 60° under more or less idle conditions and it stays around that. Beside the different desktop I use the same software. I try this now a week and never got 90°. 

I would love to continue to use KDE, which I used to use since 2005, what can I do?

Thank you!