I just bought a new case that is made for mini or micro atx motherboards. The Bitfenix Prodigy M.

At first, I got an MSI B150M Pro-VD Micro ATX motherboard, and it wasn't ideal because I got a KabyLake processor, and this motherboard requires a bios update for it to use KabyLake. Instead of finding an old cpu, and messing around with all of that, I decided to get a motherboard that was made for KabyLake.

I ordered an MSI B250M Pro-VDH Micro ATX motherboard.

Even though these are both Micro ATX motherboards, they are completely different sizes. The second one doesn't fix in the case, as it is much larger. The screw holes don't line up. I thought all Micro ATX motherboards were the same size....if not, what is the difference, and how can I tell?

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    The Micro-ATX standard specifies a maximum size, plus the positions of various elements (such as screw holes). Anything smaller that has the parts in the right place can also be called "Micro-ATX". The three holes in the corners of the B250M Pro-VDH are not screw holes, they're holes used in the manufacturing process to make it easier to handle by machines. The rest of the holes appear to be in the right places.
    – Mark
    Feb 15 '17 at 21:45
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    The first place to look is your chassis users manual, and then customer support over at Bitfenix. Feb 15 '17 at 21:56
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    @NZKshatriya, MSI lists the dimensions as "9.6 x 9.0", just slightly smaller than the maximum allowed for micro-ATX. If Amazon's dimensions were to be believed, it would be an undersized EATX board.
    – Mark
    Feb 15 '17 at 22:00
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    @mark dumps amazon, moves to newegg Yeah, you are right. Still not seeing why OP would have an issue mounting either board, aside from a case with mis-drilled screw holes. Feb 15 '17 at 22:07
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    @0-60FPS Newegg's dimensions show both being within the 9.x" by 9.x" requirements. So I am ass+u+ming that Amazon is also measuring the box. But they both should fit in the chassis scratches head Feb 16 '17 at 14:00

To directly answer your question of why they are different sizes, they are different models, and both are within the micro-atx specification.

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    "uATX" and "mATX" are the same thing -- they're both approximations to "µATX" by people who can't type a "µ" and don't want to type out "micro".
    – Mark
    Feb 15 '17 at 21:46
  • @Mark corrected answer. Feb 16 '17 at 13:58

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