Apple iMac (Early 2009) - Manual (Page 36)

36 Chapter 3 Boost Your Memory
8 Insert the new memory module into the slot with the notch facing left as shown in the
illustration.
9 Press the memory module firmly and evenly into the compartment. You’ll hear a slight
click when the memory module is seated correctly.
10 Tuck the tabs into the memory compartment.
Memory modules
Tuck the tab Tuck the tab