This step is simply the act of removing the outer case housing, which allows access to the motherboard and other internal components. Most cases are attached via standard or thumb screws, but many use pressure clips or other similar methods. If there are no visible screws holding the case housing to the frame, then consult the manual that came with your PC. If your case has multiple side panels, it is recommended that all of them be removed. If you need to open it up later, it can be a time consuming and sometimes hazardous process when performed in the middle of the motherboard installation. Also note if your case has a removable motherboard tray, or is simply a basic one-piece design.

If you are starting fresh with a brand new case, then naturally, this step is not required. For those upgrading from an older motherboard, this is the first part of the physical installation. First detach the various IDE, Floppy and ATX cables and power cord from the motherboard, and if necessary, keeping notes on their location and use. Unless they get in the way of the upgrade, leave the hard drive, CD, and other peripheral data cables attached, as well as leaving them connected to the power supply.

At this point, if your case has a fully removable tray, you can take this out as well. It's really personal preference whether to choose to remove the tray or not, and although it is an extra step, having the tray separate from the case can save you some time later on.