Discussion Mini ITX I/O shield dimensions

tesascarce

Minimal Tinkerer
Original poster
New User
Jul 29, 2020
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Hello,

Looking at the Mini-ITX spec, it looks like the I/O shield dimensions are the same for Micro ATX. In the Micro ATX spec, it says the I/O shield is 158.75mm wide by 44.45 mm tall. However, when I look at the models of cases that people have posted here (Dan A4, Lone Industries L5), the I/O shield cutouts are bigger (159.20mm x 44.20 mm for the A4, 159.15 mm x 44.85 mm for the L5).

Does anyone know why? How big should my cutout be?
 

Sirpotet

Efficiency Noob
Jun 19, 2019
7
3
The reason for making the cutout a little bit bigger than what the specification calls for is due to manufacturing tolerances. Make it big enough so that you wont get people that have cases with to small cutouts for their I/O shield.

The size of the I/O shield is the same in the whole "ATX-stack" of MOBO sizes.

// Sirpotet
 

tesascarce

Minimal Tinkerer
Original poster
New User
Jul 29, 2020
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The reason for making the cutout a little bit bigger than what the specification calls for is due to manufacturing tolerances. Make it big enough so that you wont get people that have cases with to small cutouts for their I/O shield.

Right, but looking at the tolerances they give in the ATX specification still does not give the values used in these two cases. The tolerance on the both the width and height is +/- 0.008 in (0.2032 mm), giving 158.95mm, and 44.65mm.
 

Thehack

Spatial Philosopher
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Mar 6, 2016
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J-hackcompany.com
Possibly to do with different references. For example, I use protocase reference and their numbers a bit bigger. It may also be an individually derived reference by measuring a case you have on hand.

The L5 likely uses +0.4 which likely has to do with powder coating, which adds a 0.15 mm surface thickness.