What does a PC do after switching it on before it beeps for the first time? This question will arise if the computer won't start as usual. Especially if the graphics card cannot be initialized any more, you'll need a tool that lets you look "inside".

The BIOS of the computers have a built-in aid in diagnosis that outputs every step of the power-on selftest (POST) to the PCI bus. The POST-code display (also called Port 80-display) uses a two-digit display to show the hexcode that can be translated to the error message with a table of messages from the BIOS vendor.

A lot of faults are caused by the power supply. Five LEDs show the condition of all voltages on the PCI bus.

The PCI POST-Code Display has been developed in cooperation with service technicians who had the chance to make experience with other boards like this. One basic problem of those cards is that their displays face down if plugged into a tower. The PCI POST-Code Display has all displays in a place that's easily visible even in dark tower setups. The colours of the LEDs for power supply diagnosis have been chosen to be the same as the cable colours that come out of an ATX supply for the most important voltages: orange for 3.3V, red for 5V and yellow for 12V. The visible size of the display of 13mm (0.5 inch) is bigger than most other displays. As opposed to other solutions, this display will not show random data if it's not initialized. It'll be switched off until the first valid POST code has been written by the BIOS.