Summary

With these parts and some cutting you too can mount a mATX motherboard in the NR200!

This mod is reversible even after the cut is made thanks to the printed parts, but keep in mind the first PCIE slot will be unusable in the modded configuration. The first PCIE slot on my motherbaord was a 1X slot so it doesn't really matter.

Before putting anything in the case you'll need to remove the AC plug from the back of the case and extend the motherboard IO cutout up 20.32 mm. You don't need to be that exact but this is how much the motherboard is offset by the standoff brackets.

Secure the standoff brackets to the inside of the case with screws, then screw the motherboard into the plastic standoffs.

With the motherboard and IO shield installed you can now reattach the power socket. Use two power socket retainers to hold the power socket in the extra space below the IO shield with screws. This can be a little tricky but they should secure and center it to the bottom edge of the IO shield cutout once you tighten the screws. See the pictures for more detail