Attention
Do not open your computer or attempt any repair before reading and understanding the "Important safety information" in the ThinkCentre Safety and Warranty Guide that came with your computer. To obtain a copy of the ThinkCentre Safety and Warranty Guide, go to the Lenovo Support Website.

This section provides instructions on how to install or replace a memory module. Your computer has four slots for installing or replacing DDR3 DIMMs that provide up to a maximum of 16 GB system memory. When installing or replacing a memory module, use the following guidelines:

• Use 1 GB, 2 GB, or 4 GB DDR3 DIMMs in any combination up to a maximum of 16 GB.
• Install memory modules in the sequence of DIMM 1, DIMM 3, DIMM 2, and DIMM 4. See "Locating parts on the system board".

To install or replace a memory module, do the following:

1. Turn off the computer and disconnect all power cords from electrical outlets.
2. Open the computer cover. See "Opening the computer cover".
3. Pivot the optical drive bay assembly upward to gain access to the memory slots.
4. Locate the memory slots. See "Locating parts on the system board".
5. Remove any parts that might prevent access to the memory slots.
6. Open the retaining clips.

If you are replacing an old memory module, open the retaining clips and gently pull the memory module out of the memory slot.

7. Position the new memory module over the memory slot. Make sure that 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.

8. Go to "Completing the parts replacement".