power consumption specs for Optiplex 9020

I am trying to locate and understand specifications for typical power consumption and maximum (startup) power consumption for the Optiplex 9020.  Is the 290W power supply the correct number to assume for either of those power consumption figures?

I just need some approximation of the normal and maximum working loads in either watts or amps so I can estimate the total power consumption needs for a large exhibit with many components, some of which will be similar to the Optiplex 9020.  Maximum is important because of the potential for many devices to be powered up simultaneously, if that makes sense.