C-State is effective and this may cause symptoms.
In short, C-State is a function that makes a function that sleeps unused functions while the PC is running.
For that reason, various functions are sleeping and the PC is in a state that it is not moving at full spec.
Especially C-State is effective for laptop battery to extend battery time.
Even on a mini desktop PC, I think that it is structured close to a notebook PC, so C – State may be valid as it is.
C-State is different from power saving mode of PC.