@Tom:
Thanks for your answer. So your cpu runs hot when your coolant is under 35°C. Never water cooled before so I didn't know this is usual.
Got normal room temp aswell about 21-23°C.
I'm reading the temp sensors with HWiNFO64. In the BIOS the cpu temp is jumpy or jolty. 30, 38, 33, 40, 36...