Motherboard standoff dimensions

thedudeabide

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I have been looking all over the internet to no avail...maybe I didn't look hard enough.

What is the full specifications of a standard ATX motherboard standoff?
I am intending to buy a taller standoff and is faced with the dilemma of choosing the correct external width.

Example:
UDFbYr9.png

I have seen options ranging from 3.2mm to 7mm, and have no idea which is the ATX standard.
 
Solution
According to the ATX 2.1 standard, the standoff provided has to be a minimum of 6.5mm and the external cross section has to fit within a 10mm x 10mm area around the standoff hole. There's a lot of variation (as you've discovered) to how various manufacturers meet those specs, but as long as the mounting screws match the standoff screw wells (usually 6/32 or M3 thread size) it doesn't really matter what the external width is as long as it's within the 10mm x 10mm max size requirement.

yumri

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Sep 5, 2010
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The reason for that is there is no standard for the external width of a stand off for the ATX motherboard. I am assuming this off of the ATX Specification at http://joule.bu.edu/~hazen/LinuxCluster/atx_201.pdf to this though i am unsure if that is the newest version of the ATX standard but it should be close enough as most if not all ATX boards are the same.
Go to page 8 in that .pdf link for what you are looking for also and you will see and if it isnt there there is always the other 19 pages to read.
 

thedudeabide

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Hi yumri, based on the link you provided, it states that the mounting holes have a diameter of 0.156 inches (3.9624mm). However, what about the standoff diameter? I believe usual standoffs that comes pre-installed in cases are hexagonal. What is the width of the standoff that will fit the mounting hole so that the motherboard can "sit" on it?
 
According to the ATX 2.1 standard, the standoff provided has to be a minimum of 6.5mm and the external cross section has to fit within a 10mm x 10mm area around the standoff hole. There's a lot of variation (as you've discovered) to how various manufacturers meet those specs, but as long as the mounting screws match the standoff screw wells (usually 6/32 or M3 thread size) it doesn't really matter what the external width is as long as it's within the 10mm x 10mm max size requirement.
 
Solution

thedudeabide

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Nov 16, 2014
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Hi volcanoscout, thanks for your input. I do have another query.

When I am mounting my mATX motherboard to my case's (HAF 912 advanced) standoffs, I can feel my motherboard "latching" to it, therefore knowing that it is in place. Does it work for any standoffs within the external width of 10mm x 10mm?
 


The best I can say is that it should. I couldn't guarantee that, of course - I've run into too many "standard" pieces and parts that should have fit but didn't. You pick the best parts that you can based on your available information, then cross your fingers and try it. Oh, and keep the packaging and receipts, just in case...
 

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