When the Ross NK-3G72 frame is fully populated as 72x72 with 3G SDI inputs and output cards, the total power consumption exceeds the output capability of the 100W external power supply.
To prevent problems when the frame is fully populated, Ross Video has developed a new lower power version of the output card (NK-O3G72). To keep the total power consumption below 100W, there should be no more than seven of the older output cards in the frame.