Apple Mac Pro (Early 2008) - Manual (Page 61)

Chapter 3 Making a Good Thing Better 61
To install a PCI Express card:
1 Open your Mac Pro and remove the side panel (see page 39).
2 Lay your Mac Pro down on a soft, clean cloth to avoid scratching it or the work surface.
3 Unscrew the captive screws in the PCI bracket and remove the bracket.
· WARNING: To avoid damaging internal components or the components you want to
install, always turn off and then unplug your Mac Pro. Do not attempt to install items
while it is plugged in. Let your Mac Pro cool down for 5 to 10 minutes before you
touch the internal components, which may be very hot.