Why does the cooler work jerky on a monoblock?

Question

Cooling systems

The cooler works strangely on my Dell monoblock, it looks like someone is revving the car. That is, at first it sharply gains momentum and then stops. This was not the case before. Everest shows CPU: 60b Hard: 55. There are 3 coolers in the monoblock and one of them constantly disappears or appears in evereste.
Tell me what could be the matter?

Answer 1

The lubricant needs to be changed - the old one has become frozen.