Apple Mac Pro (Mid 2010) - Manual (Page 78)

78 Chapter 3 Making a Good Thing Better
10 Replace the PCI bracket under the brace and tighten the screws to secure the card.
NOTICE: If you remove a card and don’t install a replacement, place a port access
cover over the empty slot to keep foreign objects out of the enclosure. An uncovered
slot affects the airflow that cools the internal components and may cause damage.
Brace
PCI bracket
11 Replace the side panel, following the instructions starting on page 52.
NOTICE: Always replace the side panel after installing components. Your Mac Pro
doesn’t operate properly without the side panel in place.