Dell Optiplex 780 solid orange light

Ebenezer Yeboah,

Check the diagnostic LED's 

Diagnostic LEDs

A WARNING indicates either potential damage to hardware or loss of data and tells you how to avoid the problem. WARNING:
The diagnostic LEDs only serve as an indicator of the progress through the POST process. These LEDs do not indicate the problem that caused the POST routine to stop.

The diagnostic LEDs are located on the front of the chassis next to the power button. These diagnostic LEDs are only active and visible during the POST process. Once the operating system starts to load, they turn off and are no longer visible.

The system now includes pre-POST and POST LEDs in an attempt to help pinpointing a possible problem with the system easier and more accurate.

A NOTE indicates important information that helps you make better use of your computer. NOTE:
The diagnostic lights will blink when the power button is amber or off, and will not when it is BLUE/GREEN. This has no other significance.
A NOTE indicates important information that helps you make better use of your computer. NOTE:
Some issues share quad pack codes (Diagnostic LEDs). Be sure to verify Power Button LED with customer as well.
A NOTE indicates important information that helps you make better use of your computer. NOTE:

Power Button Lights on the table below could be either BLUE or GREEN, depending on the system model.

Light Pattern Problem Description Suggested Resolution
Diagnostic LEDs Power Button LED
Diagnostic LEDs are all off. Power button LED is off. The computer is either turned off or not receiving power. Reseat the power cable in the power connector on the back of the computer and the electrical outlet.
Bypass power strips, power extension cables, and other power protection devices to verify that the computer turns on properly.
Ensure that any power strips being used are plugged into an electrical outlet and are turned on.
Ensure that the electrical outlet is working by testing it with another device, such as a lamp.
Ensure that the main power cable and front panel cable are securely connected to the system board.

Diagnostic LED number 3 is illuminated. Power button LED is off. A possible system board failure has occurred. Unplug the computer. Allow one minute for the power to drain. Plug the computer into a working electrical outlet and press the power button.

Diagnostic LED numbers 1 & 3 are illuminated. Power button LED is blinking amber. A possible system board, power supply, or peripheral failure has occurred. Power off computer, leaving the computer plugged in. Press and hold the power supply test button on the rear of the power supply unit. 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 power supply test button.If it illuminates, there could be a problem with a peripheral.
If the LED still does not illuminate, remove the PSU connections from the system board, then press and hold the power supply 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 power supply.

Diagnostic LED numbers 1, 2, & 4 are illuminated. Power button LED is amber. No CPU present. Reinstall the CPU and restart the system. If the computer still fails to boot, inspect the CPU socket for damage.

Diagnostic LED numbers 3 & 4 are illuminated. Power button LED is amber. Memory modules are detected, but a memory power failure has occurred. If two or more memory modules are installed, remove the modules, then reinstall one module and restart the computer. If the computer starts normally, continue to install additional memory modules (one at a time) until you have identified a faulty module or reinstalled all modules without error. If only one memory module is installed, try moving it to a different DIMM connector and restart the computer.
If available, install verified working memory of the same type into your computer.

Diagnostic LED numbers 2 & 3 are illuminated. Power button LED is amber. A possible CPU or system board failure has occurred. Replace the CPU with a known good CPU. If the computer still fails to boot, inspect the CPU socket for damage.

Diagnostic LED numbers 2, 3, & 4 are illuminated. Power button LED is amber. BIOS may be corrupt or missing. The computer hardware is operating normally but the BIOS may be corrupt or missing.

Diagnostic LED number 1 is illuminated. Power button LED is amber. A possible system board failure has occurred. Remove all peripheral cards from the PCI and PCI-E slots and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.

Diagnostic LED numbers 1 & 4 are illuminated. Power button LED is amber. Power connector not installed properly. Reseat the 2x2 power connector from the power supply unit.

Diagnostic LED number 2 is illuminated. Power button LED is amber. Possible peripheral card or system board failure has occurred. Remove all peripheral cards from the PCI and PCI-E slots and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.

Diagnostic LED numbers 1 & 2 are illuminated. Power button LED is amber. A possible system board failure has occurred. Disconnect all internal and external peripherals, and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
If the problem persists, the system board is probably bad.

Diagnostic LED numbers 1, 2, & 3 are illuminated. Power button LED is amber. A possible coin cell battery failure has occurred. Remove the coin cell battery for one minute, reinstall the battery, and restart.

Diagnostic LEDs are all off. Power button LED is blue. The computer is in a normal on condition.
The diagnostic lights are not lit after the computer successfully boots to the operating system. Ensure that the display is connected and powered on.

Diagnostic LED number 3 is illuminated. Power button LED is blue. A possible processor failure has occurred. Reseat the processor.

Diagnostic LED numbers 3 & 4 are illuminated. Power button LED is blue. Memory modules are detected, but a memory failure has occurred. If two or more memory modules are installed, remove the modules (see your service manual), then reinstall one module (see your service manual and restart the computer. If the computer starts normally, continue to install additional memory modules (one at a time) until you have identified a faulty module or reinstalled all modules without error.
If available, install working memory of the same type into your computer.

Diagnostic LED numbers 2 & 4 are illuminated. Power button LED is blue. A possible graphics card failure has occurred. Reseat any installed graphics cards.
If available, install a working graphics card into your computer.

Diagnostic LED numbers 2 & 3 are illuminated. Power button LED is blue. A possible floppy drive or hard drive failure has occurred. Reseat all power and data cables.

Diagnostic LED numbers 2, 3, & 4 are illuminated. Power button LED is blue. A possible USB failure has occurred. Reinstall all USB devices and check all cable connections.

Diagnostic LED number 1 is illuminated. Power button LED is blue. No memory modules are detected. If two or more memory modules are installed, remove the modules (see your service manual), then reinstall one module (see your service manual) and restart the computer. If the computer starts normally, continue to install additional memory modules (one at a time) until you have identified a faulty module or reinstalled all modules without error.
If available, install working memory of the same type into your computer.

Diagnostic LED numbers 1 & 3 are illuminated. Power button LED is blue. Memory modules are detected, but a memory configuration or compatibility error has occurred. Ensure that no special requirements for memory module/connector placement exist.
Ensure that the memory you are using is supported by your computer.

Diagnostic LED numbers 1 & 2 are illuminated. Power button LED is blue. A possible expansion card failure has occurred. Determine if a conflict exists by removing an expansion card (not a graphics card) and restarting the computer.
If the problem persists, reinstall the card you removed, then remove a different card and restart the computer.
Repeat this process for each expansion card installed. If the computer starts normally, troubleshoot the last card removed from the computer for resource conflicts.

Diagnostic LED numbers 1, 3, & 4 are illuminated. Power button LED is blue. A possible system board resource and/or hardware failure has occurred. Clear CMOS.
Disconnect all internal and external peripherals, and restart the computer. If the computer boots, add the peripheral cards back one by one until you find the bad one.
If the problem persists, the system board / system board component is probably bad.

Diagnostic LED numbers 1, 2, & 3 are illuminated. Power button LED is blue. Another failure has occurred. Ensure that all hard drive and optical drive cables are properly connected to the system board.
If there is an error message on the screen identifying a problem with a device (such as the floppy drive or hard drive), check the device to make sure it is functioning properly.
If the operating system is attempting to boot from a device (such as the floppy drive or optical drive), check system setup to ensure the boot sequence is correct for the devices installed on your computer.