Apple yesterday released Xserve LOM Firmware Update 1.2 for the Early 2008 Xserve, addressing "spurious voltage and fan speed warnings."
This update includes changes to the Lights-Out Management environment of the Xserve (Early 2008). It addresses issues that cause frequent power supply and fan notifications to be sent.
This update is strongly recommended for all Xserve (Early 2008) systems.
Apple also provides a supplementary support document which offers full instructions regarding installation of the update. The update weighs in at 719 KB and requires OS X 10.5.6.