Computers are good at calculating and never blunder if given just a decent amount of time to calculate with decent hardware. Humans have positional understanding and principles that allow us to find the best moves, often without calculating much of anything. So if a human wins, it's because our understanding predicted what the computer did not have enough time to calculate.
As Kasparov said, computers use 98% calculation and 2% understanding. The opposite is true for humans.
is it me or when you look at some of the old matches against computers ie hydra, deep blue .... the main trump of the computer was unbelievable processing power? and now its gotten to the stage where computers have become the kid in the playground no one wants to play with anymore, which is sad because i loved the idea these matches.
my idea is take processing power out of the chess computer arms race... just have a yearly qualifying tournament to play the best human(s) in the world but have all machines on standardised hardware be it a 1 or 2 ghz processor for example and a limited ammount of ram to make the compettion about software vs human intelect, opposed to being "look at me ive got more processors".