THE NUMBER OF TIMES we’ve forgotten this little plate. Now you’ve got everything out the way, you can install the backbone of your system: the motherboard. First, open the box and find the rear I/O plate, located below the board with the accessories. It’s a rectangle that goes in the back of the case to protect your I/O from damage. Look at your motherboard, see which side the holes need to be for each portion of I/O (audio is almost always closest to the GPU slots), then push the I/O bracket into place, from the inside of the chassis. It should click into place quite easily. Some of the more padded brackets can take a bit of extra force to get to sit correctly, and some premium mobos have I/O shields pre-attached, so you don’t have to worry about those.