All three vendors offer free applications on their Websites, which help customers to select the right UPS product:

• APC UPS Product Selector
  The APC product selector offers a wide number of options, including detailed component information, peripherals, desired battery backup runtime and future hardware-upgrade possibilities.
• Eaton/Powerware UPS Selector
  Eaton's UPS selector worked well, but the component list in expert mode is somewhat outdated, as it recognize AMD Athlon 64 X2 or Intel Core 2 processors. Then again, the expert mode also determines the plug type and multiple peripherals.
• Belkin doesn't offer a UPS selector tool on its Website.

Dos And Don'ts

Spending time defining the right power level for your UPS is unnecessary. On the one hand you should be sure that the UPS can output the power required to run your system and equipment in case of a power outage. On the other hand, it has to be able to maintain power for the period of time you or your system needs to shutdown properly. The UPS selection utilities by APC and Eaton/Powerware are really helpful, but you can also do the math yourself if you can guesstimate the power requirements of your system components. Since UPS products have become rather affordable, we recommend opting for something slightly above your current requirements - just in case.

There are some devices you really should not run on an UPS. It is typically a good idea only to attach hardware to the UPS that absolutely must be shutdown properly. This may include a network switch, probably even an external storage or backup device. For servers, it typically doesn't include a display (you'd shutdown the system remotely anyway). We also recommend not to run multiple displays via your UPS, or you will have to pick a really powerful one. Using the main display in a dual- or multi-display setup will usually do it. Avoid running laser printers on your UPS, as their power-on power can be too high, causing an overload.

A functional battery is the key element of a reliable UPS solution, hence it is important to replace them before they reach end of life. All three vendors recommend replacing it after a period of three years. We've had UPS units running on their first battery for much longer, but you should still replace the battery after the specified period. The UPS vendors usually take care of shipping costs for aged batteries.