Dell PowerEdge R910 - Manual (Page 7)

Getting Started With Your System
5
Securing the Power Cable(s)
Bend the system power cable into a loop as shown in the illustration
and secure the cable to the bracket using the provided strap.
Plug the other end of the power cable into a grounded electrical outlet
or a separate power source such as an uninterrupted power supply (UPS)
or a power distribution unit (PDU).
Turning On the System
Press the power button on the system and the monitor. The power indicators
should light.