Lenovo ThinkCentre A61 - Manual (Page 14)

Locating components
Figure 3 will help you locate the various components in your computer.
1 Fan plenum, fan, and heat sink 7 Battery
2 Microprocessor 8 Power supply
3 Optical drive 9 PCI adapter connector
4 Hard disk drive 10 PCI Express x16 graphics adapter or
PCI Express x1 adapter connector
(some models)
5 Diskette drive 11 PCI Express x1 adapter or PCI
Express x16 graphics adapter
connector (some models)
6 Memory modules (2)
Figure 3. Component locations
6 Hardware Installation and Replacement Guide