Below is some information which may assist in fault finding with the Axol POST card. None of these are faults with the POST card or with the system under test, they are characteristics which a user may not be aware of. Knowledge of these may help to avoid making incorrect decisions during a test.
With PCI slots the PCI bus is driven by a PCI bridge which is usually a chip on the motherboard which handles the complex protocols required by a PCI system.
This bridge may need to be initialised by the CPU before the PCI bus becomes functional which can cause a problem early in booting.
If the PCI bridge is not yet up and running then the POST codes being sent out may not be able to pass through to the POST card. While we haven't found any motherboards which exhibit this problem, it is a potential problem which users should be aware of. This problem, where it exists, is a motherboard characteristic and all PCI POST cards will suffer from it.
The Axol POST card does not identify itself to the BIOS in order not to interfere with the conditions of the test. If the POST card were to identify itself then the BIOS would attempt to install drivers and allocate resources which would change the conditions and might mask any problem in the system.
If the BIOS turns off the clock to the PCI slot which is occupied by the POST card then the POST card will, quite correctly, measure the CLK as being 0MHz. However, if the clock is not running then the POST card will be unable to latch the POST code being sent out by the BIOS.
The POST card will also be unable to download new BIOS information using the AxolPOST software as the slot has been disabled by the hardware.
The BIOSes we have seen which exhibit this behaviour also have an option in the BIOS setup program (under a title such as "Clock/Frequency control" or "Auto detect DIMM/PCI clock") to enable or disable this "empty slot detection". It is necessary to disable this detection (i.e. the BIOS will not look for empty slots and switch off the clock) to allow the POST card to see the POST codes throughout and to download BIOS data.
We have come across one case where the Axol POST card indicated that the power was good (it was measured to be within spec. during the test) yet the power supply was faulty. The problem was that the voltage rails from the supply were really in spec. as indicated by the POST card. i.e. the POST card worked. However, the power supply itself had a faulty monitor which indicated the power to be bad when the supply warmed up even though the voltages were all good. This signalled "power bad" to the motherboard which then reset. This "power good" signal is not accessible to the POST card so cannot be monitored.
So, if the POST card indicates a good ATX power supply but other things point to a power failure then it is worth checking this "power good" signal.
Axol POST card full description.