Tips for Buying an UPS
 

Your expensive computer and the more important data in it could be rendered useless due to power surges, spikes and brownouts. This is exactly why it’s best to have a UPS (which comes with a built-in voltage stabilizer blocking energy surges that could damage your computer) that is designed to firewall you against such power disturbances.

http://www.pcmech.com/article/tips-for-buying-a-ups/