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41 minutes ago, Snagoot said:
As others mentioned an ATX case will 90% of the time also support mATX, it really is just a short ATX motherboard, when you go to mount in an ATX case you just end up not using the bottom 3 standoff mounting points.
Here is my mATX motherboard in a ATX mid-tower case:
I recommend using PCPartPicker to find a case you like.
All cases shown here will support mATX as I selected that within the compatibility filter:
This said I would get an mATX mini or mid tower, as an mATX motherboard looks small in a big case and is not required.
These options are mATX specific towers: