What purpose does the IO shield on computers serve? I have been reading a lot of articles (mostly forums) on the internet and can't seem to find a definitive answer.
1) Shield to keep electro-magnetic radiation inside of the case
2) Dust Cover / Air circulation director: The fan in the power supply shall draw air throughout the entire case and not just along the short way from the I/O area to the power supply that's usually right above.
3) Aesthetics: No ugly hole.