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I'm interested in building my own computer. I saw a motherboard and CPU that I want to buy from Tiger Direct.

My question is has to do with computer cases and motherboards.

  1. Are all motherboards one size? i.e. 15" x 15"
  2. If they're not, can any motherboard go into any computer case?
  3. If not, will I need to purchase hardware to fit a motherboard into a computer case.
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Motherboards are various sizes, en.wikipedia.org/wiki/Computer_form_factor. I've not built enough to say for sure, but I have a microATX in a case that can hold a standardATX with no issues. –  Rob May 2 '12 at 18:23
First of all, this is great information, thanks to all of you that answered. –  coson May 2 '12 at 19:08

6 Answers 6

up vote 22 down vote accepted
  1. Motherboards follow standard specifications.
    These specifications include many different metrics and details, such as motherboard dimensions, features, etc.
    Modern computer chassis (cases) are ATX standard. Most of the cases you will be looking at are ATX. However there are options around this.

    • ATX motherboards will always fit into ATX cases.
    • microATX motherboards should always fit into ATX cases (but some cases are dumb, so check first).
    • miniITX is another specification, which you will probably not deal with, and it does not fit into ATX cases.
    • Wide ATX motherboards typically will not fit into standard ATX cases, so if you want a wide motherboard, also known as Extended ATX, you will need a specific case that supports it.
  2. Read 1

  3. Fitting a motherboard into a case is for the most part straight forward. There are some things you will need to know.

Take these into account:

  1. I/O shield.
    The I/O shield / I/O ports are the ports that have the USB ports, the network port, the sound ports, and stuff like that. Each motherboard will come with a metal sheet that has holes that correspond to the ports for your motherboard. You will see in the case that it already has one, pop it out and use the one provided with the motherboard.
    Make sure you install the I/O shield as one of the first steps, before putting the motherboard in. If you do not, you will have to remove the motherboard to insert it. Also pay attention to the "tabs" on the I/O shield -- these are supposed to touch the top of the connectors on the motherboard, to reduce EM emissions. Make sure you don't trap them against the case.

  2. Risers.
    All cases will come with "risers", they are little screw like things which make it so the motherboard safely secures to the case without grounding the motherboard.
    Make sure you match up all the riser spots in the case with the motherboard holes. The hole positions on the case and motherboard are standardized. Then make sure each hole on the motherboard has the corresponding riser in place, so you can screw it down to them when the motherboard is in place. Some holes will not be necessary, this is why checking positions first is necessary.

  3. Connect all power connectors on the motherboard, and reference the manual to make sure the ones you are plugging in are necessary. Also make sure to follow the "front IO" guide in the manual, this is so the power/reset/HDD LED are properly setup.

That's most of it. If you get stuck, look up howtos online to fill the gap.

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I've never heard of a "reiser", but in these parts we call them "standoffs". (And it seems Wikipedia agrees) –  Shinrai May 2 '12 at 18:24
@shinrai some people's kids... >.> –  BloodyIron May 2 '12 at 18:25
I've heard standoffs called risers, but not often. –  Rob May 2 '12 at 19:13
Pay attention to the stuff about the I/O shield. –  ultrasawblade May 2 '12 at 19:16
en.wikipedia.org/wiki/Mini-ITX 'The four mounting holes in a Mini-ITX board line up with four of the holes in ATX-specification motherboards, and the locations of the backplate and expansion slot are the same (though one of the holes used was optional in earlier versions of the ATX spec). Mini-ITX boards can therefore often be used in cases designed for ATX, micro-ATX and other ATX variants if desired.' (note that I dont have real life experience with this. I was looking into buying a mini ITX based system earlier and had read this) –  Akash May 4 '12 at 17:59


All motherboards are NOT a single size. It sepends on what type of it is ( ATX, mini-ATX, Extended-ATX, Ect ).


You purchase a motherboard that will fit the specficiations of the computer case you have. What type of motherboards a computer case fits is outlined in its specifications.


You cannot purchase "hardware" to fit a motherboard designed to fit in a case designed to fit say a smaller motherboard.

Just do your research...

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Motherboards have standard sizes

Common ones are

  1. ATX
  2. mATX
  3. Mini ITX

In decreasing order of size

A smaller motherboard can be installed in a bigger case, but not the other way around

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Motherboards and computer cases come in a Form Factor. There are a number of different form factors, a good overview is our friend Wikipedia: http://en.wikipedia.org/wiki/Comparison_of_computer_form_factors

While it is possible to fit a smaller form factor into a larger case, this tends to depend on the available 'screw holes' in the computer case. Most cases can fit a couple (if not all) form factors.

The biggest problem can be the connectors on the back of the computer, these (naturally) come from the motherboard. To get rid of any problems of connectors not fitting through your computer case, almost all motherboards come with a metal insert to replace the one that came with your case.

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Several aspects of a motherboard (including its dimensions and location of mounting holes) are determined by its form factor.

Most motherboards for desktop computers have the form factor ATX. A full-size ATX motherboard measures 12 × 9.6 in (305 × 244 mm).

Every motherboard and computer case you purchase should specify their form factors. If they match, there should be no problem. However, an oversize graphics card or CPU cooler can still be a tight fit. In my last build, I needed a set of pliers to bend things a little.

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Hello There! Good news is that with newer hardware the motherboard size should not be to much of a problem, all name brand computer cases will have holes for each motherboard type. Just ensure if you are going with a full size mother board ( vs a mini board ) that the case is designed for full size ( which shouldnt be a problem )

Your tower should also come with the stand-off's and correct screws to use. Just make sure you put in your back plate before the motehrboard is my only other advice. No additional hardware would be required apart from a screwdriver =D

Good luck

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