Apple Xserve Intel (Late 2006) - Manual (Page 44)

44 Chapter 2 Installing or Replacing Components
Replacing the Battery
The Xserve uses a CR2032 lithium coin cell battery to preserve settings such as the date
and time when the system is not connected to power. If the date and time change
unexpectedly or other system settings are lost, you might need to replace the battery.
For best results, purchase a replacement battery from an Apple-authorized service
provider.
The negative ( – ) side faces away from the power supply.