Optiplex 780 will not boot: 1 & 3 lights blinking & Power Button Blinking Amber

[Jameel_4]

My dell optiplex 780 sff wont turn on, power button blink orange, 1,3 led blink green. Replaced cpu but same behavior.

 

[Dark Lord of Tech]

Usually a failed PSU or board.
A possible system board, power supply, or peripheral failure has occurred.
http://www.dell.com/support/Article/us/en/04/SLN284978/EN
More here.​