Sorry, thought I put it in. It's 9020

What model Optiplex do you have?  Diagnostics aren't the same from PC to PC.

The answer I get from A reference guide to the Dell OptiPlex Diagnostic Indicators is a little vague.

So there's going to be some troubleshooting.

First, try replacing the size 2032 CMOS (motherboard) battery with a new one and see if that makes any difference.  Bad batteries can cause ridiculous problems.  How to Perform a BIOS or CMOS Reset and Clear the NVRAM on Dell Computers  Note: Always make sure PC is unplugged whenever working on the inside of it.  

Next:  How to Run a Power Supply Unit Self Test On a Dell Desktop or All-in-One Computer   Dell BIST Video   Notes: Make sure all external peripherals are disconnected.  If PSU test button gives the green light when pushed, internal peripherals should be good; possible bad PSU.  Green light doesn't always mean good PSU 

Under normal circumstances, a steady blinking amber power light can mean bad PSU.  A bad PSU on its way out can still spin the fans when the test button on it is pressed.

Editing note:  Above post has been added to from the original.