Hi, please refer to this article.[URL] the power cable removed from the PSU with the issue, the unplug the PSU from the system and plug it back. If the system persist, change the power source to another one. (You said The problem started happening after we changed to a different UPS.) Hope this helps and have a good one. ​
Hello, I have a Dell Power Edge 720xd where I'm seeing the following when I click on Power Supplies. The light on the Power Supply is still lit, but is there a chance that this could be anything else other than a bad power supply? The problem started happening after we changed to a different UPS. [IMAGE]  
Power Supply Failure Power Edge r720xd