H100 stopped cooling out of blue.

Hello. Yesterday I turned off my pc like usual and went to sleep. Today, in the morning when I tried to start my PC, I got CPU fan error. Went to bios and saw that CPU temp was 80c. Thought it was termocompound but I re-applied it and it's still the same. I touched one tube and it was kind of hot while other one was pretty cool. Coolers are spinning like they're supposed to.

What are possible reasons of this happening and what am I supposed to do.