POST stands for Power On Self Test. When your computer first turns on, it performs a POST. The POST tests the presence of the CPU, CMOS, Video, Memory, etc. If there’s a problem with any of the tested components, the computer will beep. There may be different patterns of beeps which will help you to narrow down what specifically is the problem. BIOS versions can differ, so check the documentation to understand what the beep codes are trying to convey to you.
If the computer fails before the beeps are emitted or before any error messages appear on screen, you can install what is called a POST card. Just plug a POST card into an expansion slot on the system and the card will show a hexadecimal 2 digit readout as the system goes through the POST process. The motherboard manual will have a reference sheet to let you know what the hexadecimal readout refers to. See what the readout says right before the computer fails.
