Lenovo 3980 - Manual (Page 73)

Figure 3. Component locations
1 Front audio and USB assembly 6 Heat sink
2 Hard disk drive 7 System board
3 System fan assembly 8 Battery
4 Optical drive 9 Memory modules (2)
5 Microprocessor
Locating parts on the system board
Figure 4 “System board part locations” on page 68 shows the locations of the parts on the system board.
Chapter 8 . Replacing FRUs 67