An expansion card mounting assembly includes a mounting structure and a circuit board coupled to the mounting structure. Expansion cards are mounted on a top side and a bottom side of the circuit board and secured at opposite ends by a moveable plate of the expansion card mounting assembly. The mounting structure includes an opening along a length of the expansion cards that allows air to flow over the expansion cards in multiple directions including a vertical direction. The moveable plate and mounting structure are configured to allow a position of the moveable plate on the mounting structure to be adjusted to mount expansion cards having different lengths in the expansion card mounting assembly.