You need to cut off the back plane of the case (where the ports are) and replace it with the one supplied using rivets (which are not supplied). You then attatch a side panel for the 1200 to sit on.
You also need to cut off the panel with the slots from the original back panel and screw that onto the new back panel.
After all that it's just a case of removing the case speaker and plugging everything in.
It only takes about 20 minutes to change the panels.
