You have just purchased a new Dell PowerEdge R520 Rack Server. The server is equipped with two Xeon E5-2400 CPUs, 32 GB RAM, four 1 TB SAS hard drives, and two 750-watt power supplies. You have a 21-inch LCD monitor connected to your server. You want a UPS to keep your server running in the event of a power failure for up to 20 minutes. You prefer a rack-mounted solution. Use the UPS selector tool at APCs Web site (a well-known UPS vendor). The UPS selector is at www.apcc.com/tools/ups_selector/. Determine which model UPS will work well for this server, and state your reasons.