It's complicated.

Computers can scale, you can make a computer much larger than a human brain.

Computers really just do binary math. For those who don't know, it's basically determining whether or not 1 or 0 should change, or stay the same, based on an algorithm. We don't know (or at least, I haven't read that we know) how brains actually store and process information.

Computers are very fast at doing "simple" calculations with definite answers. A pocket calculator can do math faster than you can with 100% accuracy. On the flip side, analyzing and reacting to incomplete information is the forte of the human brain. We still haven't made a computer than can fit in a car and drive better than some of the dumbest people on the planet manage to do, while fucking around on their phones at the same time.