They were all ranging in the constant low 4s if I remember correctly. We figured as the psu ages it may need adjusting. There was a lower voltage threshold it would reach where the boards in the stack would start to have com issues, before shutting down completely probably due to a protection feature. Hopefully your repaired board fixes it. Com issues can be a nightmare on the galaxy IIIs, maybe they fixed some of the issues on the IV, I've never seen one.