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Which UPS to the Rescue?

The importance of how long a UPS will power a system when the AC fails varies depending on the user. Some will need only time to save files being worked on, or to allow a safe shutdown while the system is unattended. Others may want the ability to continue working through a power outage. If you want more than 10 to 15 minutes of emergency power supply, you should consider a UPS rated at 750VA or greater.

We tested the UPS battery life using a Pentium MMX-200 system with 32MB of memory, a 27GB hard drive, a CD-ROM drive, and a 17-inch monitor--a relatively light load. All three UPSes ran as long as their vendors claimed. The MGE Ellipse lasted the longest, with 13 minutes, 33 seconds of run time; the IBM OfficePro placed second, with 12 minutes, 6 seconds; and the CyberPower 500SL managed only 11 minutes, 10 seconds. (Keep in mind that faster PCs with more peripherals will present a heavier load and will result in shorter run times.)

At the very least, all three units will give you time to save your work, fire off a couple of e-mails notifying others of your predicament, and shut down safely. If that's what you want from a UPS, the CyberPower 500SL's shorter run time amounts to a negligible difference, considering its low street price.

IBM, CyberPower, and MGE provide two-year warranties and liability insurance in case your equipment is damaged due to product failure. IBM tops the list, with $50,000 worth of coverage for connected equipment, followed by CyberPower at $40,000 and MGE at $35,000.

The CyberPower unit offers the best value, but if style and size are important considerations for you, you might go with the snazzy MGE Ellipse. Users wanting more control might opt for IBM's OfficePro, which kept our test system alive longer than the CyberPower, and offers the most advanced features of the three.