Apple Mac Pro (Early 2009) - Manual (Page 71)

Chapter 3 Making a Good Thing Better 71
4 Press the button on the PCI slider and move the slider to the left, which moves the
retention bar.
5 Remove your new card from its static-proof bag and hold it by its corners. Don’t touch
the gold connector or the components on the card.
Did You Know?—Installing a Full-Length PCI Card
It may be easier to install a PCI card if you remove the hard disk drives and carriers
(see page 59), and remove adjacent cards. Make sure the end of the card goes in the
appropriate card guide before aligning the card with the PCI slot and completing the
installation.
Button Retention bar PCI slider