system
A chat on subreddit /r/pcmasterrace
human
Some mineral oil PCs are passively cooled and stay around 60 degrees when in full use. Only require a pump and fans on a radiator if you use parts that run hot.
gpt
Correct. Oil allows heat to transfer away from hot components way better than air, turning the entire case into a giant heat sink. 

I hope one day I'll be able to build a mineral oil PC.