I built a new PC and installed a water cooling system for the first time. After about a minute from start-up, I hear an annoying noise. It comes from the region where the pipes lead to the radiator. To speak of a "pumping" noise with a water pump is somehow, well...I'll call it a regular, thumping noise. It is quite annoying and drowns out the fans. Is this noise normal? Will it subside during operation? I have mounted the radiator on top. Does this play a role? My PC setup is currently without a GPU due to the current availability. So I can't see anything and can't adjust anything. Because of a possible DOA return, it would still be good to know whether such a noise is normal or whether I should replace the water cooling system. I would be very pleased to receive an answer, thank you very much!