Nice poly caps 😀 . Have you kept the original value or used lower capacity ones?
Bad caps can bloat even on NOS/NIB boards, so the seller didn't necessarily lie to you.

For the no-boot problem, try disabling everything related to power management in the BIOS (a long shot, but worth trying).

Also try with another CPU, I remembered that one of my socket A processors exhibits something similar, didn't investigate as much as you did with yours, but the system doesn't boot at first attempt with that particular CPU installed, it needs a reset then everything's ok. No FF code when stuck, though. I think it stays at "-- --".

quicknick wrote on 2020-06-21, 22:51:

Also try with another CPU, I remembered that one of my socket A processors exhibits something similar, didn't investigate as much as you did with yours, but the system doesn't boot at first attempt with that particular CPU installed, it needs a reset then everything's ok. No FF code when stuck, though. I think it stays at "-- --".

I agree ! Try a plain P-100 or 133 and see what happens. If it still hangs at boot disable the cache in BIOS and see what happens.

I have a similar same type of motherboard but the baby ATX style.
I think it had a soft CPU setup in bios.
I would try to “clear the bios” first.

I purchased a bunch of these motherboards and some had bad caps and do not work.
So I would definitely replace the bulging capacitors.

My setup
AMD K6-lll+@500mhz., Voodoo 3000 (desktop)

quicknick wrote on 2020-06-21, 22:51:

Nice poly caps 😀 . Have you kept the original value or used lower capacity ones?
Bad caps can bloat even on NOS/NIB boards, so the seller didn't necessarily lie to you.

For the caps I have used exactly same specs, just switched to electrolytic polymers for better reliability. Also, I have switched 10uF small electrolytic caps to ceramic ones of the same capacitance and voltage. When this board first came in, it looked like someone already had tried to clean up the smudge it had, because the spot was already partially cleaned up, I had to use carburetor cleaner to remove it completely. In this case, I myself wouldn't publish it as New Old Stock and fully working, I would clearly describe its defects: puffy capacitors, smudge, possibly non-working. So in that sense, I am not really happy with the seller, too bad the board arrived a year ago and I didn't open it after few months later.

Regarding the cold boot problem - this board has been nothing but frustration. After many more attempts and trials, the SDRAM socket seems to have started having false contacts so RAM is recognized in 1 out of ~40 attempts after moving it around slightly (would stop at post code C1). I have tried different CPU - also Pentium 1 MMX but 166Mhz, but it exhibits same cold boot problem, just now with faulty RAM socket it's more frustrating to make it POST successfully again. So I'm putting this off for dismantling/parts, to go on with another project. 🙁

So I have this board too. I got it from someone from around 2001-2002 I believe, which I think they had a problem with it. I did a quick test with the board and 500 MHz K6-2 it came with, and thought it seemed to be working and I put it away in storage. I'd been piecing together some parts, and decided that this might be worth trying again.

I installed a voodoo 3 in it and tried it a few weeks ago, before I saw this topic. I too saw something strange. It seemed like periodically, a cold or warm it would not boot anymore, and could never use the reset button without getting a black screen. It also seem like I could "fix" it by switching it off at the switch at the back, waiting a minute, switching the back switch on, waiting a minute, then pushing the power button, that would always work. Another thing seemed to also do the trick would be to reset the cmos.

I checked these things before I found the "fix":
Different video cards -- no difference, both AGP and PCI
Fresh CMOS battery -- no difference
Different power supply -- no difference

I did notice that DIMM slot 2 was "bad". The slots seem rather they have harsh pins, maybe scrapping alot of the module's connector. I cleaned up the connectors on the DIMM modules, and DIMM1 and 3 continue to be fine, but DIMM2 still no go yet. Yes, I tried swapping around different modules, and trying one at a time. I may check it more closely but I don't really mind right now.

So I put it away and brought it out again this weekend. I thought the Voodoo3 and board combo was fine if I used by trick, but I still was sometimes hitting the problem, going through video cards again, and then searching online to find your post here. I was starting to notice a slow degrading, that depending on how many times or ways I would reset, it would eventually not full boot or stop booting altogether. I started clearing the CMOS every time, and it would then boot like magic. I am not sure how that had a play in this, but it is not really stable now is it? So with the replies suggesting trying another CPU, I thought it was possibly time to rule that out.

So I had a K6-2 500MHz in there which came with the board, but I also have a K6-2+ 500MHz. So I suppose if there was a voltage regulation or power issue running at 2.2V, would running at 2.0V be better? I tried it, and it worked! I could start up as much as I wanted and hit reboot as much as I wanted.

So then I started wondering about the fact that the K6-2+ has integrated L2 cache. Maybe it's an L2 cache issue when using the motherboard. So I decided to install a Pentium MMX 233MHz at 2.8V. And that also works fine... So it's not an L2 cache issue, maybe... It's looking like just a bad CPU that the board came with.

Maybe I knew that the CPU was suspect when I got it, but that was a long time ago 😀 I installed WinME and it's working quite well and fast. I see no issues so far with the K6-2+.

So it's a slight possibility in your case, it's simply not making proper contact in the DIMM slot, due to fault in manufacturing. But I have not tested the Pentium MMX totally with the OS now on just yet. Maybe stability issues would eventually creep in if using the L2 on the motherboard, I don't know.

So my thought is your issue is possibly is the DIMM slots, or in a lesser possibility, some kind of weird compatibility issue with the CPU/cache?

EDIT:
Before I forget. The caps are original, but they are in excellent condition when I checked them over this past weekend. The board was stored well.