Motherboard
Find the motherboard standoffs that should have come with the case. They are
screws, usually brass, with large hexagonal heads that are tapped so you can
fasten screws into the top.
Remove the I/O Shield from the back of the case where the ports on the
back of the motherboard will fit, and put in the I/O Shield that came with your
motherboard. There may be small metal tabs on the inside of this face plate, if
so you may have to adjust them to accommodate the ports on the back of the
motherboard.
Some case styles make it difficult to install the motherboard or the CPU
with the power supply installed. If the power supply is in your way, take it out
and set it aside (we’ll put it back in later).

Now locate the screw holes on your motherboard and find the corresponding
holes on the motherboard plate (or tray) in the case. Put a standoff in each of
these holes on the tray and position the motherboard so that you can see the
holes in the top of the standoffs through the screw holes in the motherboard.
Now is the time to make sure the ports on the motherboard are mating
with the backplate you just installed, and make any necessary adjustments.
The small metal tabs are intended to make contact with the metal parts of the
connections on the back of the motherboard and ground them, but you may
have to bend these tabs a bit to get the ports all properly mounted, this is
where those needlenose pliers may come in handy.
If you have trouble lining up the screw holes, double check that you have
the standoffs in the proper holes on the tray. With lower quality cases there are
sometimes alignment problems and you may have to forgo one or two screws.
If this is the case, make sure you remove the corresponding standoffs.
Now fasten a screw through each of the motherboard screw holes into the
standoffs underneath. These screws should be snug but not tight, there is no
reason to torque down on them, hand tight is fine, otherwise you can damage
the motherboard.
There, the motherboard is in, now it’s time to plug the other components
into it.