George McFly,  The BIOS and iDRAC firmware work together to inventory the components installed in the system. Then the total system power is estimated by adding up the power for each component in the system. The overall power consumption of the system can be estimated for removable components such as processors, memory, and hard drives. It is these together that will then be compared to the power threshold and will trigger the alert.  Let me know if this helps. 
Anybody else have issues with the power supply  and when you have to go to a higher watt power supply. it seems like as you build them up, at some point there is the need to go to a higher watt. is it the processor size, memory, or both. i had 128 gbs, and the 5600 series for a proc and after a hour or so, was given the error that power supply coldn't handle config. 87w power supply fixed issue, but am curious for future
per710 power supplies