Put your PC into a slick ATX case

Start by migrating the primary parts. First, mount the PSU in the new case. The simplest method is to slide it in from the inside; if that's impossible, unscrew the rear plate bracketing the PSU area and insert the PSU through the back of the case. Refasten the plate and screw in the PSU.

Now, insert the motherboard and screw it into place. When aligned correctly, your motherboard's external ports will protrude from the back of the case through a rectangular aluminum panel with cutaways (called the I/O shield). An I/O shield should come with the new enclosure. Compare it to the one on your old case. If they differ, use your previous I/O shield.

Next, reinstall any PCI and graphics cards in the slots they occupied before. In our case, the I/O shield, the motherboard, and the PCI cards all sat on the enclosure's handy removable tray; we reinstalled the tray in the case at this time. Some cases require that the tray be installed in the case before the cards can be repatriated.