Diagnostics Display

Some manufacturers like EPoX and ABIT are marketing motherboards with a diagnostic LED display soldered directly to the motherboard. This display operates in the same way as diagnostic cards sold on the market. If the computer does not turn on or freezes during start up, we just have to get the number that is displayed and look it up in the handbook to find the probable cause of the trouble.

POST displayFigure 4: Diagnostics Display.

Some other manufacturers, like DFI and MSI, use a more simple diagnostics device made of four LEDs. The principle is the same, if you computer doesn’t turn on or freezes during start up you just have to take a look at the diagnostics LEDs and see on the motherboard manual what is going wrong based on which LEDs are turned on and which LEDs are turned off.

POST LEDsFigure 5: Diagnostics LEDs on a DFI motherboard.

POST LEDsFigure 6: Diagnostic LEDs (four LEDs on the left corner) from MSI.


Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.