one of the metal shields on the rear panel that covers the expansion slot. Be sure to remove the appropriate shield for the expansion card you are installing.
b.If you are removing a PCI Express x1 card, hold the card at each end and carefully rock it back and forth until the connectors pull free from the socket. Lift the card straight up (1) then away from the inside of the chassis (2) to remove it. Be sure not to scrape the card against other components.
Removing or installing an expansion card 15