While sometimes POST cards seem no more helpful than a "Magic 8 ball" or going through a box of fortune cookies, I have found them more useful than I ever thought they would be, even with a a weird BIOS you can't get POST code table for, purely relying on "make number go bigger" mode. It seems to be universal that the early codes are related to the core of the system, CPU/RAM, the middle codes the chipset and bare essentials and the later codes more to do with i/o and peripherals. So it kind of transforms fault finding from a kind of "Blind man's buff" game in like a massive empty warehouse with unknown number of participants, ( https://en.wikipedia.org/wiki/Blind_man%27s_buff ) to a game of "Marco Polo" which is in the confines of a pool and players have to call out "Polo" so you know they are there. In the first instance, it's easy to get frustrated and give up because you know very little about the number of issues to resolve. In the second you go kinda voice by voice and clear everything. If you get bogged down with a stubborn unknown fault code with unknown BIOS revision, you can "take votes" from all the code tables you can find, and drill down from most common specific issue to least, and it is probably gonna be one of those. All in all though, make number go bigger, you're fixing stuff, not completely in the dark, and eventually you get there.
edit: Actually, you can do better with an unknown revision if you use your early codes found to "narrow down the tree" of code tables that match, so by the time you're on your 3rd or 4th fault to clear you have one or two code tables that seem to match everything, and if a 5th code shows up, kapow, headshot, no messing around.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.
