Asus RS740-E7-RS24-EG - Manual (Page 46)

Chapter 2: Hardware setup 2-22
7. Push the plastic lock inward from the
rear until it clicks securely in place.
5. Align and insert the expansion card into the
slot of the motherboard. Ensure that the
expansion card is seated firmly in place.
6. (Optional) Secure the expansion card with
the screw that you removed in step 3.