The Brain-Jupiter is a planet-sized theoretical computing megastructure that is capable of computing more commands than any other structure.
Swedish scientist Anders Sandberg tried to uncover this topic in 1999. A brain-computer called Zeus would be a sphere 18,000 km in diameter and 1.8 times the mass of the Earth. It would consist of structures made of nanodiamonds or diamondoids. They would form a network of nodes around a central energy core of quantum circuitry and molecular storage systems. Theoretically, the "brain-Jupiter" would perform about 10⁴² operations per second. But for now, this is just a theory about a megastructure that goes beyond human capabilities.
Link to source:
https://hightech.fm/2021/10/14/jupiter-brain