Using a Phillips P0 screwdriver, loosen the PCI Express cover retaining
plate and remove it. There is a tab at the top that the metal plate latches
into, you’ll need to unscrew the 2 screws and slide the plate down out of
the tab.
Once the metal retaining plate is removed, remove the top PCI Express
dead plate cover from the top slot as shown. Set the dead plate cover
aside, you’ll be using it in a future step.
OWC Multi-Mount
Chapter 2 - Mac Pro 667MHz Disassembly
2 MAC PRO 667MHZ DISASSEMBLY