Dell 5100cn Color Laser Printer User Manual page 220

5. Place the controller card on the table so that its edge hangs over the edge of the table and the controller card is
horizontal. Push the clips on both sides of the slot outward. Remove the memory card from the slot.
6. Insert the controller card into the printer.
7. Tighten the three screws on the controller card from the back side of the printer.