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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.

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    \$\begingroup\$ What is an IO shield? \$\endgroup\$ – Leon Heller Feb 8 '11 at 8:27
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    \$\begingroup\$ I would call it a RFI/EMI cover plate, not an "IO Shield". "IO Shield" is dangerously unspecific, particularly considering the proliferation of the use of the term "Shield" for boards that plug on to arduinos. \$\endgroup\$ – Connor Wolf Feb 8 '11 at 11:50
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    \$\begingroup\$ @Fake Name The IO shield is already established name which you will find in motherboard manuals and other computer literature. It's been in use for much longer than Arduino and similar devices. Here's an article about it. \$\endgroup\$ – AndrejaKo Feb 8 '11 at 12:17
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    \$\begingroup\$ I agree, the term is somewhat strange. Many terms in the field of computing hardware are strange and misleading. But it still seems to be popular and used by many, so I guess arguing makes little sense. (I also don't get "form factor", for example. Board outline would be so much better, imho. I have never multiplied an ATX with anything, so I really don't know what a factor does in this context.) \$\endgroup\$ – zebonaut Feb 8 '11 at 12:24
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    \$\begingroup\$ @FakeName, I get annoyed when I am interacting with someone and I tell them we need to get a shield for something and they think of arduino parts. Shields was used long before, and will be used long after, to refer to components that protect against unwanted effects. I understand that naming convention, and I do not mean to start a holy war, but an RF shield is very important. \$\endgroup\$ – Kortuk Feb 8 '11 at 14:28
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I/O shield:

enter image description here

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.

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  • \$\begingroup\$ As per keeping electro-magnetic radiation inside. What are the consequences if this is leaked? Could it interfere Wi-Fi or something..or with other electronics :S \$\endgroup\$ – irwinb Feb 8 '11 at 18:14
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    \$\begingroup\$ Could be anything, really, but for instance, the pixel clock of a VGA card is exactly where FM radio is. Interference with Wi-Fi is likely as well. You never know. As an indicator: PC hardware is very (!) cost-sensitive. Manufacturers don't spend an exta 0.3 Ct. on something that would not be absolutely required to pass certification measurements. \$\endgroup\$ – zebonaut Feb 8 '11 at 19:01
  • \$\begingroup\$ Don't forget it's bidirectional. It shields from external interference too to give immunity. \$\endgroup\$ – winny Nov 14 '17 at 18:19
  • \$\begingroup\$ How much you can radiate is regulated for consumer products, this is part of that. \$\endgroup\$ – old_timer Dec 27 '17 at 12:09
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It's simply for covering the back of the computer, and for shielding your inputs and outputs from being jarred around and damaged when you're plugging in and unplugging things. Some people on this thread seem confused. Because it has "shield" in the name, people think it's shielding against current or EMF. It has nothing whatsoever to do with current, or EMF interfering with radios or anything else. I use radios, I also have no covers on my computer, side front or back. To add to that, the radio I have right now is inside my computer. It's really only aesthetic, there to look good because as a shield for your inputs and outputs most of them are fairly useless without being actually attached to the board and solid rather than thin and flimsy.

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    \$\begingroup\$ You are so wrong. A quick look at any shield would show you that you are wrong. The "fingers" around the openings are certainly not there for looks - they are ugly. Those springy fingers are there to ensure good electrical contact - shields need a good ground contact. They are thin and flimsy because that is good enough to block the RF that the PC generates. \$\endgroup\$ – JRE Nov 11 '17 at 7:52
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For posterity's sake, I'll add something new, here. I'm finding this thread in 2017 after typing the question into Google.

Before now, I've read a few POVs stating that the IO shield isn't necessary at all. In fact, I went to a parts shop recently after losing mine assuming it was an absolute requirement. I was set to buy a replacement motherboard, because I couldn't find a replacement IO shield anywhere. (I admit I was an idiot). The rep at the counter told me not even to bother with the IO shield and definitely not to buy another motherboard from him.

He told me that IO shields are included so that motherboards can pass inspections in some countries. Some countries have strict "no exposed components" policies. If a mobo ships without a shield, then the manufacturer is forcing the recipient/builder to leave components exposed via the IO hole in the back of the case.

So, it might be overkill. "No exposed components" might be a policy designed to make sure that mobos, GPUs and the like are properly housed. That little hole in the back might not be dangerous, practically, but technically it violates the code outlined by the policy. So IO shields.

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    \$\begingroup\$ IO shields are not necessary, for you anyway. But for the rest of us who like to use radios, they are necessary. A cable without a shield turns into a nice antenna an radiates any frequencies on the motherboard into the air. The shield ties the cable to ground and attenuates this noise. Antennas work both ways, the shield also prevents external noise from interfering with the digital signals. \$\endgroup\$ – Voltage Spike Feb 7 '17 at 23:59
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    \$\begingroup\$ "No exposed component" is not a real policy. There are policies for EM Interference and there are standards for mechanical protection of parts/users (IP codes). IO shields help with the first one, otherwise they would be made of plastic. \$\endgroup\$ – Wesley Lee Feb 8 '17 at 0:04
  • \$\begingroup\$ Wesley are you sure it's never a real policy? The example the rep gave me of a country employing that policy was the UK. laptop2d thanks for the insight. I didn't know that about radio signals. \$\endgroup\$ – Ryan Keeler Feb 20 '17 at 23:36

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