I am not too sure what you expect to change, maybe you can elaborate?
As for a real world example: Take the
Viper I linked above. You can see that I have the hangar, the cargo hatch and the fuel scoop on 5, and these get turned off when I deploy hardpoints (they are marked in red). Now put these on group 4 instead and see what happens: Now in addition to those three modules, my shield generator and shield boosters, which were already on 4, are marked red, indicating that when I deploy weapons, my shields get turned off. Because I moved the hatch, scoop and hangar from priority 5 to 4, and now the ship turns off group 4 instead of 5 (because there is no 5), as I am over the power budget. Note that all my modules combined actually draw 103 percent of the available power - which isn't possible of course (that figure is in the lower left corner of the EDSY screen).