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.
Actually oil coated contacts would not be a problem. Practically all electrical contacts form a thin oxide layer on exposure to air. Also air borne contaminates such as cigarette smoke will also leave a non conductive coating on a surface. To overcome this problem connectors are designed to forcefully slide over each other and scrape the surface clean down to the metal contact. This is why it takes a lot of force to push on high pin count connectors. For example: if the insertion force is 1 oz per pin then a 16 pin connector will take 1 pound of pressure to mate and a connector with 160 pins will take 10 pounds.
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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.
Actually oil coated contacts would not be a problem. Practically all electrical contacts form a thin oxide layer on exposure to air. Also air borne contaminates such as cigarette smoke will also leave a non conductive coating on a surface. To overcome this problem connectors are designed to forcefully slide over each other and scrape the surface clean down to the metal contact. This is why it takes a lot of force to push on high pin count connectors. For example: if the insertion force is 1 oz per pin then a 16 pin connector will take 1 pound of pressure to mate and a connector with 160 pins will take 10 pounds.