There's only two reasons for this:   (1) 12V bus is overloaded ... did you install something that draws significant power from the 12V bus recently? If so you have an easy fix (remove whatever you added)   (2)  the power supply has gone bad & is now failing to supply as much current to the 12V bus as it should do. In which case the PSU needs to be swapped out for a good one; they're not repairable unless you have solid technical understanding of power supplies and a well equipped workshop.
Hello,    can someone please help me find a solution my pc keep blinking and orange light on the power bottom and what I’ve notice is that when I unplug the 4 pines (12vlt) cables and press the PSU diagnostic bottom the fans and every other thing are able to start but when I replog the 4 pines cable the orange light start blinking what can be the problem ?
Dell optilex 790 ci3 blinking orange light on power bottom