Congratulations!! Happy it did eventually start to work.
Let us know how it behaves and throw in a few pics to make us appreciate this board 😀

Have fun.

thanks. for the help and advice.
I'll tell if everything finally works ok.
I hope to have some luck with my other older systems as well

As unfortunately many years ago I threw away the old case I had, I can't put them together like that. I don't want to use a more modern case. but my real plan is to mount them on a kind of plank, guts out, as an exhibition. I have designed several ways to do it. even make it transportable. Before I only thought of including the 486 (with an am5x86) and the Pentium (MMX) but now I can include on the opposite side this Super Socket 7 and with a lot of luck the PII, so I will have 4 systems in a rolling "exhibition"

I leave some representative images of what I'm talking about.

Right now I am now looking at big (big) Philips 21" CRT on sale. For now I have a 17" Acer that I have to check because it has a failed solder or something like that and the brightness increases a lot sometimes... which is solved with a hit on the side, 🤣. For my beloved Samsung SyncMaster 997 I have to Look for a replacement IC for its power supply.

I forgot to say. When soldering point "1" on the rear side (see picture some answers above), the fluid tin "collected" towards the leg of the capacitor, "cleaning" the contact (I don't have a wick yet) and revealed that, in that place, it does not touch vein "A" either. vein "A" does not touch leg ¨1¨ on either side !!
????

As a side note, I tell you that I use a mobile phone as a makeshift microscope, with low latency streaming the image to the PC . I see it there in the browser. I can transmit the image even at the maximum resolution and magnification the camera allows, although the limit is imposed by the optics, for example, the "macro" capacity and the ability to focus quickly and accurately. Although I want to make a more specialized application, at least to manipulate the image in real time, some post-processing and quality improvements.

well, still stuck at "Checking NVRAM"
the battery is OK.
already tested with a different ram stick (128MB PC133). will have some more, all different, to test tomorrow . update: 2 more different ram sticks (32, 128), same result
and with a different CPU, a K6-2/450.
and different video card, just in case.
I will upgrade the BIOS and see what happens. it is a little hard to get the chip off the socket, hahahah

if nothing work , that could mean fight again with the capacitors

kinetix wrote on 2023-10-03, 01:42:

well, still stuck at "Checking NVRAM" the battery is OK. already tested with a different ram stick (128MB PC133). will have some […]
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well, still stuck at "Checking NVRAM"
the battery is OK.
already tested with a different ram stick (128MB PC133). will have some more, all different, to test tomorrow
and with a different CPU, a K6-2/450.
and different video card, just in case.
I will upgrade the BIOS and see what happens. it is a little hard to get the chip off the socket, hahahah

if nothing work , that could mean fight again with the capacitors

https://twitter.com/nanochess/status/16201538 … BDhQXuiMjC1BFWg

You need a new BIOS chip, this one cannot be written on anymore. It happened a few times to members here.

MMM...
I don't think so (I hope not).
I just read that EPROM chip is rated at 10 000 page write cicles
Knowing its previous owner, I doubt the PC that motherboard was used on was reconfigured, turned on and off, or rebooted enough times for that to happen.

kinetix wrote on 2023-10-03, 20:28:

MMM...
I don't think so (I hope not). Knowing its previous owner, I doubt the PC that motherboard was used on was turned on and off, or rebooted enough times for that to happen.

Worth a try. Or disable L2 cache.

according the datasheet of this EPROM chip , it is rated at 10 000 page write cycles.
assuming that storing the configuration parameters represents a "page write" (I don't think so) even less do I think they have made 10K configuration changes
or, if every reboot means a write, that would be 27 years of use with a daily on-off/reboot.
So I think even less that this is the problem.
I can't disable the cache because I can't enter the BIOS. its stuck before you can press the key.
When power on the keyboard flashes quickly once. I already tried another keyboard and it is not the problem.
I'll try an ATX power supply instead of the AT I'm using now.

anyway.
I have reviewed datasheets, and the EPROM of my AOpen AP53 motherboard (older and has not wanted to work again after been put away 20+ years), apparently it is compatible with that of this Gigabyte
the oldest is AT29C010A
the newest is SST29EE010
It will be something that I will try in the next few days as I have time, and I also have to do it with the help of a friend who has a programmer.

Success!
I reprogrammed the bios with the latest stable bios version, and it worked. Before it had version 1.3, now it has F6.
Before doing that I compared the original data from the eprom with the same version from the "theretroweb", and saw a section of empty data (spaces) with several small differences. But the "fat" data was identical.
Now I just need to do some stress and stability tests.