Asus P2-P5945GC - Manual (Page 28)

2-12 Chapter 2: Basic installation
2. Remove the metal cover opposite the slot that you intend to use.
3. Insert the card connector to the slot, then press the card firmly until it
fits in place. Secure the card with a screw.
4. Reinstall the PCI riser card assembly. Make sure that the riser card
connector sits properly on the motherboard PCI slot.