a server system and cluster system using the same . the server system includes power supply module for providing first operation power , an energy - storing module for providing a stored power , power management module coupled to power supply module and energy - storing module for receiving first operation power and providing a second operation power , or for receiving the stored power and providing a third operation power , at least one motherboard having internal memory module for receiving second operation power or third operation power , and an external memory module coupled to the at least one motherboard . the present invention retains the data in the memory and the operating messages while a power failure occurs suddenly in the server so that server system is capable of restoring the data and the operating messages before the power failure to simplify the system and reduce the cost .