Computer case vent size (Score 1)

The Holes have to be small. The primary function of a computer case is to prevent radio frequency noise from getting out. Physics dictates that to this the holes must be no larger than one quarter of the length of the shortest wavelength you need to stop. Which is in turn a function of the speed of the fastest oscillator in the computer. Did you ever read the label "...complies with FCC Part B..." and the standards are a lot less tolerant now for CE than the FCC ever wanted.