Lenovo ThinkCentre M55e - Manual (Page 32)

2. While holding the left rear of the computer chassis down, pull upward on the
handle provided to remove the PCI riser assembly including any adapters that
are already installed.
3. Open the adapter latch and remove the failing adapter.
4. Remove the new adapter from its static-protective package.
5. Install the new adapter into the expansion connector into the PCI riser.
6. Ensure the adapter is fully seated into the adapter connector.
24 Hardware Replacement Guide