Isn't it a matter of computer speed or comparison rate?
No. It's a matter of having a human brain, which works far, far better than any computer will for the next 100 years at least.
Some say that one day computers reach the power of human brain
Not in your lifetime, nor in your children's lifetime, and probably even not in your grandchildren's lifetime, even if they're not born yet. The problem is that we know only a microscopic fraction of a percent of a percent of how the human brain works, and it will take a long, long time to build up that knowledge. Even in a century, we will still have huge gaps in our knowledge of how the brain works.
