Dell PowerEdge R810 Getting Started With page 7

Securing the Power Cable(s)
Attach the power cable retention bracket on the right bend of the power
supply handle. Bend the system power cable into a loop as shown in the
illustration and attach to the bracket's cable clasp.
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.
5
Getting Started With Your System