Dell OptiPlex 360 (Late 2008) - Manual (Page 90)

90 Memory Modules
Replacing or Adding a Memory Module
CAUTION: Do not install ECC memory modules.
CAUTION: If you remove the original memory modules from the computer during a
memory upgrade, keep them separate from any new modules that you may have,
even if you purchased the new modules from Dell. Match the specifications of the
memory modules you are installing. Otherwise, your computer may not start
properly.
NOTE: If you install mixed pairs of PC2-5300 (DDR2 667-MHz) and PC2-6400 (DDR2
800-MHz) modules, the modules function at the speed of the slowest module
installed. The specifications for the memory module are listed on a label on the
module.
NOTE: This procedure assumes that you have completed the removal procedure
first.
1 Install a single memory module in the connector labeled "DIMM1," the
connector closest to the processor, before you install modules in any other
connector.
1 label
1