Source : Free On-Line Dictionary of Computing

lots of MIPS but no I/O
     
        Used to describe a person who is technically brilliant but
        can't seem to communicate with human beings effectively.
        Technically it describes a machine that has lots of processing
        power but is bottlenecked on input-output (in 1991, the IBM
        Rios, a.k.a. RS/6000, is a notorious recent example).
     
        [{Jargon File}]