Lenovo THINKCENTRE 6019 - Manual (Page 98)

5. Position the replacement memory module over the memory connector. Make
sure the notch 1 on the memory module aligns correctly with the connector
key 2 on the system board. Push the memory module straight down into the
connector until the retaining clips close.
6. Go to “Completing the FRU replacement” on page 112.
92 Hardware Maintenance Manual