Optiplex 760, blinking amber light, 1&3

Binking Amber power LED = The power supply is receiving power from the source but is unable to properly distribute it to the components.

1 & 3 Diagnostic LEDs = A possible system board, PSU (power supply unit), or peripheral failure has occurred.
* Power off computer, leaving the computer plugged in. Press and hold the PSU test button on the rear of the PSU. If the LED next to the switch illuminates, the problem may be with your system board.
* If the LED next to the switch does not illuminate, disconnect all internal and external peripherals, and press and hold the PSU test button. If it illuminates, there could be a problem with a peripherals.
* If the LED still does not illuminate, remove the PSU connections from the system board, then press and hold the PSU button. If it illuminates, there could be a problem with the system board.
* If the LED still does not illuminate, the problem is probably with the PSU.