Apple Mac Pro (Mid 2010) - Manual (Page 52)

52 Chapter 3 Making a Good Thing Better
9 Replace the side panel.
When you replace the side panel, make sure the latch is up. Hold the side panel
securely so it stays in place as you push the latch down.
Place the side panel
in the slot and then
push to close.
NOTICE: Always replace the side panel after installing components. Your Mac Pro
doesn’t operate properly without the side panel in place.