Dell Dimension XPS 50 Reference Manual page 26

NOTE: Use a UPS to protect your computer only. Connect other devices, such as a
printer, to a separate power strip providing surge protection. The length of time that
the battery can supply power following an AC power loss decreases with additional
hardware.
UPS systems can cost a few hundred dollars to several thousand dollars, depending on
the operating time they provide when AC power is lost. UPS systems with 5 minutes
of battery power let you conduct an orderly shutdown of the system, but are not
intended to provide continued operation. A UPS system should be Underwriters Lab-
oratories (UL) safety-approved.
1-8 Dell Dimension XPS Txxx and Txxxr Systems Reference and Troubleshooting Guide