[PeterisP]

A cubic foot size system running on 100 watts can implement a human-level intelligence (obviously, we have such a system running in our brains), so the theoretical limit is at least there.

It's extremely implausible that a similar system (perhaps requiring 100 times more power and/or space) couldn't implement a human-level intelligence running 100 times faster; doing an hour-and-a-half equivalent of thinking, planning and research analysis every minute.

It's extremely implausible that a bunch of similar systems (a thousand?) couldn't possibly be put in a single place, wired together so that they can effectively communicate, and designed to cooperate without any distrust.

IMHO even this configuration (which doesn't even assume that intelligence that's a bit superhuman is possible at all) would be sufficiently scary to threaten humanity.

[colordrops]

These statements are extremely hand-wavey and provide no evidence for their claims.