Lenovo ThinkCentre A57e - Manual (Page 37)

4. Position the replacement memory module over the memory slot. Make sure the
notch 1 on the memory module aligns correctly with the slot key 2 on the
system board. Push the memory module straight down into the slot until the
retaining clips close.
5. Go to Chapter 4, “Completing the parts replacement,” on page 37.
Figure 25. Installing the memory module
Chapter 3. Installing options and replacing hardware 29