We can define the 3 states of No Post, No Power & No Video as follows:
No Post (Power On Self Test) - Once the Power button is pressed, the system will go through a series of internal checks. If any of these checks should fail, the system will not boot to Windows and the diagnostic LED's and or Power button LED should illuminate to indicate the potential problem.
No Power - Once the Power button is pressed, no Diagnostics LED's will illuminate nor the Power button LED, the system will not boot to Windows and there will be no signs of power to the system, keyboard or mouse.
No Video - Once the Power button is pressed, the system will power on and proceed to the POST checks where you may see the Diagnostic LED's illuminate for a short period of time, the Power button LED will illuminate as well as the keyboard LED's but there will be no signs of video on the Screen/Display. You may hear the Windows login melody but the screen is blank.
The computer is either turned off or is not receiving power.
Reseat the power cable in the power connector on the back of the computer and the electrical outlet.
If the computer is plugged into a power strip, ensure the power strip is plugged into an electrical outlet and is turned on. Also, bypass power protection devices, power strips, and power extension cables to verify the computer turns on properly.
Ensure the electrical outlet is working by testing it with another device.
Use a verified working Power cable.
Ensure that the main power cable and front panel cable are securely connected to the system board.
All power supply units include a self-test ability in an isolation mode. A test button and LED are on the side of the unit where the AC plug is located. Ensure the power cable is connected to the supply & Press the test button to test the PSU.
If the PSU LED does not illuminate, remove the PSU cables from the system board and test again. If the LED still does not illuminate when the test button is pressed, the PSU is possibly faulty.
If after removing the cables from the system board and the PSU LED illuminates, one of the attached devices or components could be faulty. Remove all attached components, reattach the PSU cables and using the PSU test button, install each component individually to test.
Dell Enhanced Pre-boot System Assessment, ePSA has been significantly improved with a view to streamlining the entire diagnostic process.
During the boot process, ePSA is accessed from a cold boot by pressing the power button ON and repeatedly press the F12 key until the BIOS Boot Menu appears on the screen.
Use the keyboard up and down arrow keys to select Diagnostics on the menu and press the Enter key. ePSA begins by checking an area in system memory to insure it is safe and then loads itself into the verified memory area. ePSA then automatically begins high level algorithms on all system memory to insure integrity. ePSA next creates a graphical menu listing all discovered devices in the system.
Note: Here are some things to remember when running the ePSA Diagnostics.
While the tests are running, the pointer (mouse or touch pad) is disabled. To exit the tests, press <ESC>.
The version number of the ePSA Diagnostics is displayed in the lower right-hand corner of the screen.
The activity indicators (bars) that appear during the memory tests are not used as an indication of progress. They show the location of the memory being tested.
Any errors along with the error code are displayed on the right side of the screen under the Results Window. A pop-up message also appears if a test fails.