I have just fitted a new motherboard into my PC, and consequently had to fit a better PSU (400W ATX). Unfortunately, the three-pin PSU auxiliary output does not lose power when the PC is shut down. This means that the attached monitor, which is powered from this output, has to be turned off manually. I know it's not major, but my old PSU did this and I don't know if it is a fault or part of the functionality of the new PSU.
Any advice would be much appreciated.
I have checked the BIOS and power management, but there is nothing obvious to change.