NEC Express5800/140Rf-4 User Manual page 360

10.
Slowly close the tab to secure the PCI board.
NOTE:
Make sure that the tab is firmly locked. If the tab is unlocked,
the PCI board and/or base board may be damaged due to unstable PCI
board.
11.
Close the protect cover.
12.
Reinstall the removed components.
Upgrading Your Server 9-27