When you have to be extremely noise/fault tolerant (e.g. you can literally remove half a brain and still function normally [1]), you over-design and over-engineer the system with massive redundancies everywhere. We don't know how much information is actually encoded in these trillions of low precision synapses. Our best deep learning models tend to be very over-parametrized, and are highly compressible. A CPU is nowhere as fault tolerant but it does not have to be, because modern solid state electronics is extremely reliable (and has much wider ranges of operating conditions than human brains).

[1] https://en.wikipedia.org/wiki/Hemispherectomy