You have just purchased a new Dell PowerEdge R820 Rack Server. The server is equipped with four Xeon E5-4650 CPUs, 128 GB of 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 for up to 20 minutes in the event of a power failure. You prefer a rackmounted solution. Use the UPS selector tool at APC's Web site (a well-known UPS vendor). The UPS selector is at www. apcc. com/tools/ups_selector/. Determine which model of UPS will work well for this server, and state your reasons.