HP rp5800 Reference Manual page 39

10. If an expansion slot cover is installed in the lower slot, remove the slot cover.
CAUTION:
when removing or installing the card.
Figure 2-32
11. To remove the riser card, disconnect the hood sensor cable from the system board (1), pull back
the arm on the back of the riser card slot (2), then lift the riser card out of the riser card slot (3).
Figure 2-33
ENWW
You must remove the lower expansion slot cover to avoid damaging the riser card
Removing the Lower Expansion Slot Cover
Removing the Riser Card
Replacing the Riser Card 33